Healthy Weight & Metabolism
Physical Activity, Strength and Keeping Muscle
Preserving muscle while losing weight means that more of the weight you lose is fat and less of it is muscle and other lean tissue. Trials suggest the most dependable ways to help are adding strength work to an eating plan, eating enough protein, and keeping moving once the weight is down.
General information, not medical advice. Last updated October 31, 2026. Written by the AlternativeMed editorial team. Not medically reviewed.
Start here
- If you have not been active for a while, or you have a heart, joint or other health condition, speak to a GP or other clinician first, then start small with short walks and gentle strength exercises.
- Build up to muscle-strengthening activity on 2 days a week that works all the big muscle groups, plus regular moderate activity such as brisk walking. The NHS guideline for adults is at least 150 minutes of moderate activity a week.
- Lose weight gradually and include protein at your meals. A dietitian can set protein and calorie amounts for you, and that is safer than cutting food sharply.
Be careful with
- Fast weight loss on very little food can cost more muscle and has its own risks. Do not cut calories sharply to lose weight quickly.
- If exercise feels driven or compulsive, or you restrict food, binge, purge or fear eating, that is a reason to see a GP, not to push harder. See the page on eating disorders and disordered eating.
- Fat burners, "muscle-sparing" pills and protein powders do not replace training. Check any supplement with a pharmacist or doctor first if you have kidney, liver or heart conditions or take medicines.
Get help when
- Chest pain, breathlessness out of proportion to the effort, dizziness or feeling faint when you exercise: stop and get medical advice. The NHS says not to self-diagnose chest pain.
- Weight loss you did not intend, or weight loss that comes with weakness, tiredness or loss of strength, needs a medical check.
- A joint or muscle injury that does not settle, or pain that is sharp or getting worse.
- Worry about food, weight or shape, exercising too much, or feeling you must burn off what you eat: see a GP as soon as you can.
- You are older, have fallen or fear falling, or have osteoporosis or past fractures: ask a clinician or physiotherapist to help plan strength work.
About Physical Activity, Strength and Keeping Muscle
What this goal means
When people eat less to lose weight, some of the weight lost is not fat. Part of it is fat-free mass, which includes muscle but also water and organs. A 2022 review of 30 weight-loss studies says almost a third of lost weight is fat-free mass when nothing extra is done. Keeping muscle matters because muscle supports strength, balance, everyday tasks and independence, particularly as you get older.
This page is about that specific goal: how exercise, protein and staying active help you lose less muscle and keep the weight off. It is education, not a personal plan, and it does not set calorie or protein targets. For how to lose weight in the first place, see Lose Weight Sustainably, and for measurement see the BMI and body composition page.
1,2What it can look and feel like
The scale cannot tell fat from muscle. People who lose weight quickly sometimes notice that they feel weaker, tire sooner on stairs or find lifting and carrying harder. Others see the scale barely move while their waist shrinks and their clothes fit differently, which is a common result of adding strength and aerobic work.
NIDDK says physical activity may not have a big impact on weight loss itself, but it has important health benefits independent of weight loss. Trials back this up: aerobic exercise lowered waist size and body fat more clearly than it lowered weight.
3,4What contributes to losing muscle
The main factors named in the research are eating much less without training the muscles, low protein intake while losing weight, long periods of sitting, and age. In the trials read, programmes that added exercise to calorie restriction preserved fat-free mass, and strength and mixed training had the largest estimates.
Weight-loss medicines are a class of treatment that a doctor decides on. A 2026 meta-analysis found that the share of lost weight that was lean mass was similar with these medicines (about 25 to 39 percent) and with lifestyle programmes alone. Lean mass was a smaller share (17.5 percent) when resistance training was part of the lifestyle programme.
2,5Related conditions
Age-related muscle loss (sarcopenia) has its own page, as do overweight and obesity, prediabetes and type 2 diabetes, and eating disorders with compulsive exercise. This goal page does not diagnose or treat any of them; it points you to them so you can talk to a clinician.
Realistic expectations
Muscle is kept, not built quickly, while eating less. In the trials, adding exercise preserved on average about 0.87 kg more fat-free mass than calorie restriction alone. That is a modest, useful difference, not a transformation. Only two trials in that review measured muscle itself, so most numbers are for fat-free mass.
Results come from group averages and short to medium trials, mostly up to about a year. Individual results vary with age, starting fitness, how closely the plan is followed and what you eat.
2Who this applies to
Most of the trials were in adults with overweight or obesity who were eating less to lose weight. It is relevant to anyone losing weight on purpose, including people using a medicine prescribed for weight loss, and to older adults who want to keep strength. It is not written for children and teenagers, for whom the NHS and WHO publish separate guidance, and it is not a plan for people with an eating disorder history, who should involve a clinician first.
6,7Related conditions and symptoms
Eating disorders and disordered eating → Overweight and obesity: health context and care options → Prediabetes, type 2 diabetes and metabolic syndrome → Sarcopenia and muscle loss with age →
A manageable starting plan
An educational starting point, not a personal prescription. Adjust it to your own situation and any advice from your clinician.
Your first actions
- Check with a GP first if you have been inactive or have a health condition.
- Do strength exercises that work all the big muscle groups on 2 days a week, starting with a few gentle ones.
- Walk or do other moderate activity most days, building toward 150 minutes a week.
- Include a protein food at each meal, with a dietitian's help on amounts.
Optional additions
- Add a short walk after meals or break up long sitting.
- Join a class or ask a physiotherapist or qualified trainer to check your technique.
- Ask a dietitian whether a protein supplement would add anything to your food.
- Once you reach your goal, keep the routine going to help prevent regain.
What to track
- How many strength sessions and active minutes you do each week.
- Strength and stamina you notice, such as stairs, carrying shopping or getting up from a chair.
- Waist size or how clothes fit, if checking does not cause worry about food or weight.
- Aches, joint pain or injuries.
When to reassess
Check in every 4 weeks. If you are weaker, more tired, losing weight faster than planned, or an ache is not settling, slow down and speak to a GP or dietitian. Most trials followed people for up to about a year, so judge your progress over months, not days.
When to seek professional support
- Ask a GP before starting if you have been inactive or have a health condition.
- See a registered dietitian for eating, protein and pace of weight loss.
- Ask a physiotherapist or qualified trainer for strength technique.
- If you worry about food, weight or shape, or exercise feels compulsive, see a GP as soon as you can.
What helps
Ordered by how well the research supports each step. Evidence strength is shown on every card; precautions sit next to the advice.
Start here
Add strength training to your weight-loss plan
Moderate certaintyAddresses: Helps keep more fat-free mass while you lose weight
Why it may help: A 2026 meta-analysis of 34 trials (1,455 adults with overweight or obesity) found that adding exercise to calorie restriction kept 0.87 kg more fat-free mass than calorie restriction alone, preventing 45.7 percent of its loss. Mixed training (+1.20 kg) and strength training (+0.83 kg) were significant in the network analysis; endurance training (+0.51 kg) was not. A separate 2026 meta-analysis of 20 trials found lean mass made up about 17.5 percent of weight lost with resistance training, versus about 26 percent with lifestyle alone.
How to apply it: The NHS suggests strengthening activities that work all the main muscle groups (legs, hips, back, chest, abdomen, shoulders and arms) on at least 2 days a week. This can be weights, resistance bands, body-weight exercises, heavy gardening, yoga or pilates. Start with a few exercises and add repetitions gradually.
Who it may suit: Adults losing weight on purpose who have no condition that rules out exercise.
Precautions: Speak to a GP first if you have not exercised for some time or have a medical condition. The differences between training types were not statistically significant in the main analysis, so the best programme is the one you can keep doing. Only two trials measured muscle itself.
2,5,6,8Aim for regular moderate activity, such as brisk walking
Moderate certaintyAddresses: Smaller waist and less body fat; a small drop in weight
Why it may help: A 2024 meta-analysis of 116 trials (6,880 adults with overweight or obesity) linked each 30 minutes a week of supervised aerobic exercise with 0.52 kg lower body weight and 0.56 cm smaller waist. About 150 minutes a week at moderate to vigorous effort gave clinically important drops in waist and body fat. Aerobic work does not by itself protect muscle as clearly as strength work, but it adds to the health benefits.
How to apply it: NHS says adults aged 19 to 64 should do at least 150 minutes of moderate activity or 75 minutes of vigorous activity a week. Moderate means your heart rate and breathing go up but you can still talk but not sing. NHS Better Health says getting more active has benefits even if you start with 10 minutes at a time.
Who it may suit: Most adults; start where you are.
Precautions: Aerobic exercise was linked to about 2 more mild to moderate adverse events per 100 people, mostly muscle and joint symptoms (low certainty). Build up gradually, particularly if you are older or have joint problems.
4,6,9Eat protein at your meals while you lose weight
Moderate certaintyAddresses: May help keep lean mass, especially alongside training
Why it may help: A 2015 review (Leidy and colleagues) says higher-protein, energy-restricted diets preserved lean mass in several shorter, tightly controlled studies, while longer-term results were mixed and depended on whether people followed the plan. A 2022 review of 30 weight-loss studies found exercise plus high protein beat high protein alone for fat-free mass, so protein is a partner to training, not a replacement.
How to apply it: Include a protein food at each meal, such as eggs, fish, poultry, dairy, beans, lentils, tofu or nuts. This page does not give a personal amount; a registered dietitian can set one for your age, health and goals.
Who it may suit: Adults eating less to lose weight, particularly when also doing strength work.
Precautions: People with kidney or liver conditions or on a special diet should ask a clinician before changing how much protein they eat. The 2015 paper is a narrative review, and many long-term trials had low adherence to the planned diet.
10,1,11Additional options
Lose weight gradually
Low certaintyAddresses: Gives your body less reason to lose muscle
Why it may help: NIDDK's page on choosing a safe and successful weight-loss programme is about finding a plan that suits you and is safe. The trial abstracts we read did not cover the risks of fast weight loss on very little food, which is why a dietitian or clinician can help plan a safe pace. We did not read a trial that directly compares fast and slow loss for muscle, so this is cautious guidance, not a proven effect.
How to apply it: Ask a GP or dietitian to help you set a pace and an eating plan that suits you. Do not follow crash diets.
Who it may suit: Anyone intentionally losing weight.
Precautions: Not suitable for use as a restriction target for anyone with a history of disordered eating; see a clinician first.
3,1Keep exercising after the weight is down
Low certaintyAddresses: About 2.8 kg less weight regained in trials
Why it may help: A 2026 meta-analysis of 11 randomised trials (568 people with overweight or obesity who had lost weight) found the exercise group regained 2.81 kg less than controls (95% CI -5.12 to -0.51). The fat mass result was not statistically significant and varied a lot between trials. NIDDK suggests 150 to 300 minutes or more of activity a week, with an eating plan suited to the new weight and weekly weight checks, may help prevent regain.
How to apply it: Keep your walking and strength sessions in your weekly routine after the weight goal is reached. Choose activities you enjoy so that they last.
Who it may suit: Adults who have lost weight and want to keep it off.
Precautions: The authors call for longer follow-up and objective checks that people really exercised. Weekly weight checks do not suit everyone; skip them if they cause worry about food or weight.
12,3Take everyday steps and sit less
Low certaintyAddresses: Lower risk of early death in large follow-up studies
Why it may help: A 2022 pooled analysis of 15 cohorts (47,471 adults, 3,013 deaths) found a progressively lower risk of death with more daily steps, up to about 6,000 to 8,000 steps in adults 60 and over and 8,000 to 10,000 in younger adults. These are links in observational studies, not proof, and they are not step targets for muscle. The NHS also advises reducing time spent sitting or lying down.
How to apply it: Add short walks through the day, stand up from long sitting periods, and take stairs where you can.
Who it may suit: Most adults.
Precautions: Observational: people who walk more also differ in other ways. Build up slowly if you are inactive or have a health condition.
13,6Strength work for older adults
Moderate certaintyAddresses: Better grip strength, walking speed and fewer fall injuries
Why it may help: A 2026 meta-analysis of 13 trials (546 older adults with sarcopenia) found resistance exercise improved handgrip strength by 2.95 kg, gait speed by 0.15 m/s and chair-stand time by 1.79 seconds. A 2026 meta-analysis of 29 trials (6,367 community-dwelling older adults) found exercise reduced fall-related injuries (risk ratio 0.87) and fall-related fractures (0.56). The NHS says adults 65 and over should do strength, balance and flexibility work on at least 2 days a week.
How to apply it: Start gently with chair-based or body-weight exercises, and consider a class or physiotherapist if you have fallen or fear falling.
Who it may suit: Adults aged 65 and over, including those who are losing weight.
Precautions: Speak to a GP first if you have not exercised for some time or have a medical condition. People with osteoporosis or past fractures should ask a clinician before heavy lifting. Trials of sarcopenia mainly measured strength and function, not weight loss.
14,15,16Strength training and protein for older adults → Sarcopenia and muscle loss with age →
Still being studied
Creatine together with strength training
Moderate certaintyAddresses: Small extra gains in lean tissue and strength in trials of adults, mostly not in people losing weight
Why it may help: A 2017 meta-analysis of 22 trials (721 adults, mean age 57 to 70) found creatine added 1.37 kg of lean tissue mass compared with placebo plus modest strength gains. A 2025 meta-analysis of 8 trials in older adults found gains in lower-limb strength and lean tissue mass but not upper-limb strength overall.
How to apply it: Not recommended here; see the Remedies tab for the evidence and cautions.
Who it may suit: Not established for weight-loss muscle preservation specifically.
Precautions: The abstracts did not describe side effects. Ask a doctor or pharmacist first, especially with kidney problems or regular medicines.
17,18Whey or other protein supplements
Moderate certaintyAddresses: Small extra strength and fat-free mass with training in healthy adults
Why it may help: A 2018 meta-analysis of 49 trials (1,863 healthy adults, resistance training for 6 weeks or more) found protein supplements added 2.49 kg in one-repetition-maximum strength and 0.30 kg in fat-free mass. The benefit was smaller with older age, larger in already-trained people, and no extra fat-free mass gain was seen above a total intake of about 1.6 g per kg of body weight a day. That is what trials observed, not a target for you.
How to apply it: Food first. A powder is only a convenient way to add protein if your diet falls short; see the Remedies tab.
Who it may suit: Not established for people losing weight.
Precautions: Side effects were not described in the abstracts. Kidney and liver conditions need a clinician first.
11Resistance training for mood
Low certaintyAddresses: Lower depressive and anxiety symptoms in pooled trials
Why it may help: A 2018 meta-analysis of 33 randomised trials (1,877 adults) found resistance training was linked to lower depressive symptoms, with high variation and smaller effects in trials that blinded allocation or assessment. A 2017 meta-analysis of 16 articles (922 adults) found a smaller effect on anxiety. This is a side benefit, not a reason to rely on exercise instead of care.
How to apply it: Choose strength work you enjoy as part of your routine.
Who it may suit: Adults generally.
Precautions: Exercise is not a replacement for care when mood is low. If you feel very low or unsafe, talk to a clinician or local emergency services.
19,20Strength and bone density
Low certaintyAddresses: Higher hip bone density in adults 65 and over in pooled trials
Why it may help: A 2022 meta-analysis of 14 randomised trials in adults aged 65 and over found progressive resistance training increased leg strength and femur or hip bone mineral density (+2.77 percent), but not lumbar spine density. Heterogeneity for bone was very high, and no trial of actual fractures was read.
How to apply it: Under clinician guidance if you have osteoporosis.
Who it may suit: Older adults.
Precautions: People with osteoporosis or past fractures should ask a clinician before starting heavy lifting.
21Food & nutrition
Protein foods while losing weight
Higher-protein, energy-restricted diets preserved lean mass in several shorter, tightly controlled studies, but results over longer periods were mixed and depended on whether people stuck with the plan. Exercise plus high protein beat high protein alone. Choose protein foods you enjoy and can afford, such as eggs, fish, poultry, dairy, beans, lentils, tofu and nuts, and spread them across the day.
This page does not give a protein amount or a calorie target. A registered dietitian can set both for your age, weight, health and any medicines.
10,1Total intake matters too
In the 2018 trials of healthy adults who were not mainly dieting, no extra fat-free mass gain was seen beyond a total protein intake of about 1.6 g per kg of body weight a day. That describes what researchers observed in those trials. It is not advice for you, and it does not apply to people with kidney or liver conditions or on special diets, who should ask a clinician first.
11What the research does not show
We did not read trials showing that any single food or drink preserves muscle on its own. Eating enough overall, enough protein and training are the parts the trials tested together.
Remedies & supplements
Traditional use, laboratory findings and human trials are kept apart. "Natural" does not mean safe.
Creatine
Moderate certaintyStudied form and route: Oral supplement used alongside resistance training in studies of adults and older adults
Intended outcome: Small gains in lean tissue and strength
Human evidence: A 2017 meta-analysis of 22 trials (721 adults, mean age 57 to 70, training 2 to 3 days a week) found creatine added 1.37 kg of lean tissue mass compared with placebo, plus modest gains in chest press and leg press strength. A 2025 meta-analysis of 8 trials (482 older adults) found gains in lower-limb strength and lean tissue mass, but not upper-limb strength overall, with larger effects in trials of 32 weeks or less.
Traditional use: Not a traditional remedy; we did not read a source on traditional use.
Laboratory findings: No mechanism was tested in the abstracts read.
Limits: These trials were not in people dieting to lose weight, so they do not show that creatine preserves muscle during weight loss. Lean tissue includes water.
Interactions and precautions: Side effects were not described in the abstracts read, so we make no safety statement. Ask a doctor or pharmacist before using creatine, especially with kidney problems or regular medicines. Avoid in pregnancy and breastfeeding unless a clinician advises, because no data on this were read.
17,18Whey protein and other protein supplements
Moderate certaintyStudied form and route: Powders and shakes added to a diet during strength training
Intended outcome: Small extra strength and fat-free mass with training
Human evidence: A 2018 meta-analysis of 49 trials (1,863 healthy adults) found protein supplements added 2.49 kg in one-repetition-maximum strength and 0.30 kg in fat-free mass. The benefit was smaller with older age and larger in already-trained people. A 2022 review of weight-loss studies discussed exercise training with dietary supplements, but we did not see a clear supplement effect on muscle during weight loss.
Traditional use: Not a traditional remedy; it is a food-derived product, and we did not read a source on traditional use.
Laboratory findings: No mechanism was tested in the abstracts read.
Limits: Gains were small and mostly in people not trying to lose weight. Food can supply the same protein.
Interactions and precautions: Side effects were not described in the abstracts. People with kidney or liver conditions or on special diets should ask a clinician before increasing protein. Check products for allergens such as milk. Check with a pharmacist if you take regular medicines.
11,1HMB with whey protein and strength training
Not enough evidenceStudied form and route: Supplement studied in older people with sarcopenia
Intended outcome: Possible gains in fat-free mass and function in older people with muscle loss
Human evidence: A 2026 meta-analysis of 7 trials (472 older people with sarcopenia) found strength training with whey protein or HMB improved fat-free mass, grip strength, chair stand and six-minute walk. The authors call this promising rather than definitive because the trials were few, small and at moderate to high risk of bias.
Traditional use: Not a traditional remedy; we did not read a source on traditional use.
Laboratory findings: No mechanism was tested in the abstracts read.
Limits: Older people with sarcopenia, not people losing weight. It does not separate HMB from whey protein.
Interactions and precautions: Side effects were not described in the abstract read. Ask a doctor or pharmacist before use.
22Therapies & care
Established professional care here means a GP or other clinician who can check your health before you start, a registered dietitian for eating and protein, and a physiotherapist or qualified trainer for strength work. This page does not recommend medicines or doses. Prescription weight-loss medicines are a class of treatment that a doctor decides on, and you should never stop or change a prescribed medicine on your own.
Check-in with a GP before starting
Moderate certaintyProfessional care The NHS says to speak to your GP first if you have not exercised for some time, or if you have medical conditions or concerns, and to make sure the activity and its intensity fit your fitness. It also notes that you are more likely to have heart problems if you are older or at risk of coronary heart disease, for example if you smoke or have high blood pressure, diabetes or high cholesterol.
Who it may suit: People who are inactive, older, or who have heart, blood pressure, diabetes, joint or other conditions.
Precautions: Do not self-diagnose chest pain; see a GP if you are worried.
6,23Registered dietitian
Low certaintyProfessional care A dietitian can set a protein and calorie plan that fits your health, medicines and pace of weight loss. NIDDK's page on choosing a weight-loss programme is about a safe plan that suits you. We did not read a trial that compares dietitian care to self-directed plans for muscle, so this is general guidance.
Who it may suit: Anyone losing weight, and anyone with kidney or liver conditions, diabetes or a history of disordered eating, who should have a plan with a clinician.
Precautions: Look for a registered professional.
3Physiotherapist or qualified trainer
Low certaintyProfessional care A physiotherapist or qualified trainer can show safe technique and tailor strength work around joint problems, a past fall or osteoporosis. The NHS suggests strength exercises that build up slowly. We did not read a trial comparing supervised and unsupervised strength training for weight loss.
Who it may suit: Older adults, people with joint or balance problems, and anyone new to strength work.
Precautions: Tell them about your health conditions and any medicines.
8,16Medical weight-loss treatment
Moderate certaintyProfessional care A doctor decides whether a prescribed weight-loss medicine or other medical treatment is appropriate. A 2026 meta-analysis found lean mass was a similar share of weight lost with these medicines as with lifestyle programmes alone. The researchers conclude that muscle mass can be preserved by integrating resistance training, adequate protein intake and body composition monitoring into weight-loss programmes.
Who it may suit: People for whom a clinician considers treatment appropriate.
Precautions: This page gives no drug names or doses. Never stop or change a prescribed medicine without speaking to your prescriber.
5,24What to avoid
Habits, products and claims that can get in the way. Never stop a prescribed medicine without talking to the professional who prescribed it.
Risks that apply to most people
Cutting calories sharply with no strength work
Moderate certaintyWhy: The trials that preserved muscle added exercise to calorie restriction. Without it, almost a third of lost weight can be fat-free mass, and fast loss on very little food has its own risks.
Who it applies to: Anyone losing weight on purpose.
Try instead: Lose weight gradually, add strength work on 2 days a week, and ask a GP or dietitian to plan your pace.
1,2Jumping into hard exercise after a long break
Low certaintyWhy: The NHS says to speak to a GP first if you have not exercised for some time or have a medical condition, and to build up slowly. Aerobic exercise was also linked to slightly more muscle and joint symptoms in trials.
Who it applies to: People who have been inactive, older adults, and people with heart, joint or other conditions.
Try instead: Begin with short walks and gentle strength exercises and add a little each week.
6,8,4Personal triggers to check
Long, unbroken sitting
Low certaintyWhy: The NHS advice for adults includes reducing time spent sitting or lying down.
Who it applies to: People with desk jobs or long travel.
Try instead: Stand and move briefly through the day.
6Exercise as punishment for eating
Moderate certaintyWhy: The NHS describes exercising too much as a symptom of eating disorders, and anorexia as trying to control weight by not eating enough, exercising too much, or both.
Who it applies to: Anyone who feels they must burn off food or who feels distress when they miss a session.
Try instead: See a GP as soon as you can and read the page on eating disorders and disordered eating.
25Products that need caution
Fat burners and "muscle-sparing" weight-loss pills
Not enough evidenceWhy: We did not read human trials showing that these products protect muscle during weight loss. Some products contain stimulants. See the claim-check page for the evidence on weight-loss supplements.
Who it applies to: Anyone considering them.
Try instead: Put the effort into strength work, protein from food and a gradual pace. Ask a pharmacist before any supplement.
2Weight-loss supplements, fat burners, detox teas and vinegar: claim check →
Supplements taken with regular medicines without checking
Not enough evidenceWhy: No interaction study of creatine, whey protein or HMB with regular medicines was read. People with kidney, liver or heart conditions need advice first.
Who it applies to: People who take medicines or have these conditions.
Try instead: Ask a doctor or pharmacist before starting.
17,11Unsupported claims
"Lift weights and you can eat what you like" or "you can spot-reduce fat"
Evidence againstWhy: Trials show that adding exercise preserved some fat-free mass on average, a modest difference. They do not show that exercise cancels a calorie deficit or removes fat from one body part. Metabolism claims have their own claim-check page.
Who it applies to: Anyone planning around the claim.
Try instead: Treat strength work as a way to keep more muscle, not as a free pass.
2,3"Weight-loss medicines do not cost muscle" or "they always do"
Moderate certaintyWhy: A 2026 meta-analysis found lean mass made up a similar share of weight lost with medicines (about 25 to 39 percent) as with lifestyle alone. That is an average of trials, not a statement for any one person. Whether to use a medicine is a decision for you and a clinician.
Who it applies to: People considering or using prescribed weight-loss treatment.
Try instead: Ask your clinician about strength work and protein alongside any treatment. Never stop or change a prescribed medicine on your own.
5Common mistakes
Judging progress only by the scale
Low certaintyWhy: Fat-free mass includes water and organs as well as muscle, and the scale cannot tell fat from muscle. Waist size and strength can change when the scale does not.
Who it applies to: Anyone tracking weight.
Try instead: Also notice how you feel, your strength and how clothes fit. Skip frequent weighing if it causes worry.
4,2Stopping all exercise once the weight goal is reached
Low certaintyWhy: In 11 trials, people who exercised during weight maintenance regained about 2.8 kg less.
Who it applies to: People who have lost weight.
Try instead: Keep a weekly routine of walking and strength work.
12Evidence & safety
What the research shows
Exercise added to calorie restriction preserved on average 0.87 kg more fat-free mass in 34 trials (moderate certainty), with strength and mixed training giving the largest estimates; lean mass was a smaller share of weight lost when resistance training was included. Aerobic exercise lowered waist size and body fat more clearly than weight. Protein and creatine added only small gains in strength and lean mass, mostly in people not dieting. Exercise during weight maintenance was linked to less regain (low certainty). Most trials measured fat-free mass rather than muscle itself.
Limits of the evidence
- Only two trials in the main review measured muscle itself; most measured fat-free mass, which includes water and organs.
- Differences between training types were not statistically significant in the main analysis.
- No large, long head-to-head trial comparing strength, aerobic and mixed training for weight loss was read.
- Long-term follow-up beyond about a year for body weight and muscle was not read.
- Whether protein amounts matter equally for younger and older adults while losing weight is unclear from the abstracts read.
- Side effects of creatine and protein supplements were not described in the abstracts read.
- Observational links with death and disease cannot show cause.
- Full texts were not read for the trials; numbers come from abstracts.
Precautions and interactions
- Speak to a GP before starting if you have not exercised for some time or have a medical condition.
- Ask a clinician before starting a new exercise or weight plan if you have a current or past eating disorder.
- Ask a doctor or pharmacist before using creatine, whey, HMB or other supplements, especially with kidney, liver or heart conditions or regular medicines.
- Never stop or change a prescribed medicine, including medicines for blood pressure, heart conditions or diabetes, without speaking to your prescriber. People with diabetes should ask their clinician before changing how hard or how often they exercise or how they eat.
Life-stage considerations
- Pregnancy and after birth: the NHS says its adult guidelines are also suitable for pregnant women and new mothers, who should include strength training, and that more intense activity can start after the 6- to 8-week postnatal check if you feel able. Vigorous activity is not recommended if you were inactive before pregnancy. Weight-loss dieting in pregnancy and breastfeeding needs clinician guidance. Talk to a midwife or doctor.
- Children and teenagers: this page covers adults. The NHS and WHO publish separate guidelines for children and young people, and the weight-loss and supplement studies read here were in adults.
- Older adults: adults 65 and over should do strength, balance and flexibility work on at least 2 days a week. If you have fallen or fear falling, ask a clinician or physiotherapist to help plan it.
- Heart disease, high blood pressure or chest pain: ask your clinician before starting a harder programme.
- Eating disorder history, or worry about food, weight or shape: see a clinician before starting a new exercise or weight plan.
Warning signs
- Chest pain, unusual breathlessness, dizziness or fainting during exercise.
- Weight loss you did not intend, or increasing weakness.
- A joint or muscle injury that does not settle.
- Exercising too much, feeling you must burn off food, or fear of eating.
Claim checks
Strength training helps you keep muscle while losing weight
Moderate certaintySupported. Adding exercise to calorie restriction preserved 0.87 kg more fat-free mass in 34 trials, and lean mass was a smaller share of weight lost with resistance training. Most trials measured fat-free mass, not muscle.
2,5Exercise alone is enough to lose a lot of weight
Moderate certaintyNot supported. Aerobic exercise was linked to only a small drop in weight (0.52 kg per 30 minutes a week) but clearer drops in waist and body fat. NIDDK says activity may not have a big impact on weight loss itself.
4,3You need protein supplements to keep muscle
Moderate certaintyNot supported. Supplements added small gains in healthy trained adults; food protein plus exercise beat high protein alone in weight-loss studies. We did not read evidence that supplements are required.
11,1Creatine preserves muscle during weight loss
Not enough evidenceNot shown. The creatine trials read were with resistance training in adults and older adults, not in people dieting to lose weight.
17,18Weight-loss medicines make you lose more muscle than dieting
Moderate certaintyNot supported on average. Lean mass was a similar share of weight lost (about 25 to 39 percent) with these medicines and with lifestyle alone in a 2026 meta-analysis. A doctor decides whether a medicine suits you.
5Keeping active after weight loss prevents regain
Low certaintyPartly supported. People exercising during maintenance regained about 2.8 kg less, but the evidence is small and the fat mass result was inconclusive.
12Questions people ask
Can I lose weight with exercise alone?
Exercise is associated with small weight changes and with larger drops in waist size and body fat. Combining it with dietary changes is more common in programmes. NIDDK says physical activity may not have a big impact on weight loss itself but has health benefits independent of it.
Is strength training better than cardio for keeping muscle?
Both helped preserve muscle in a meta-analysis. Estimates were somewhat larger for programmes that included strength training, though differences between training types were not statistically significant.
How much exercise do I need?
The NHS suggests adults aged 19 to 64 do at least 150 minutes of moderate activity or 75 minutes of vigorous activity a week, plus strengthening on at least 2 days. Speak to a GP first if you have health conditions or have been inactive.
How much of the weight I lose will be muscle?
A 2022 review says almost a third of lost weight is fat-free mass without extra therapy, and a 2026 meta-analysis found lean mass was about 26 percent of weight lost with lifestyle alone and about 17.5 percent when resistance training was added. These are averages of trial groups and include water and organs, not only muscle.
How much protein should I eat?
This page does not give a personal amount. Higher-protein diets kept more lean mass in shorter, tightly controlled studies, while longer-term results were mixed. A registered dietitian can set an amount for your age, health and medicines, which matters especially if you have kidney or liver conditions.
Do I need protein powder or creatine?
No. Protein supplements added only small gains in strength and fat-free mass in trials of healthy adults, and creatine added small gains in lean tissue with training. Neither has been shown to preserve muscle during weight loss. Ask a doctor or pharmacist first if you take medicines or have kidney, liver or heart conditions.
Does walking count?
Yes. Walking counts as aerobic activity. The NHS says moderate activity raises your heart rate and makes you breathe faster, and a way to tell is whether you can still talk but not sing. Walking does not replace strengthening work on 2 days a week.
What if I use a weight-loss medicine?
A doctor decides whether a medicine suits you. A 2026 meta-analysis found a similar share of lost weight was lean mass as with lifestyle alone, and concluded that resistance training, enough protein and monitoring help preserve muscle. Ask your clinician about this and never stop or change a prescribed medicine on your own.
Does it matter if I am older?
Strength work matters more with age. The NHS advises adults 65 and over to do strength, balance and flexibility work on at least 2 days a week, and a 2026 meta-analysis found exercise reduced fall-related injuries. Start gently and speak to a GP first if you have not been active.
Can exercise be a sign of a problem?
It can. The NHS lists exercising too much among symptoms of eating disorders. If exercise feels compulsive, or you worry about food, weight or shape, see a GP as soon as you can and read our page on eating disorders and disordered eating.
References
- Effects of exercise training and dietary supplement on fat free mass and bone mass density during weight loss (systematic review). F1000Res 2022. PMID 36071711. source
- Effects of calorie restriction with and without strength, endurance or mixed training on fat-free and skeletal muscle mass in overweight or obese individuals. Diabetes Obes Metab 2026. PMID 42144246. source
- NIDDK. Choosing a safe and successful weight-loss program (last reviewed February 2024). Read 2026-10-31. source
- Aerobic exercise and weight loss in adults: a systematic review and dose-response meta-analysis. JAMA Netw Open 2024. PMID 39724371. source
- Lean mass changes with incretin therapy versus lifestyle intervention: a systematic review and meta-analysis of randomised controlled trials. Diabetes Obes Metab 2026. PMID 41877354. source
- NHS. Physical activity guidelines for adults aged 19 to 64 (last reviewed 22 May 2024). Read 2026-10-31. source
- World Health Organization. Physical activity fact sheet. Read 2026-10-31. source
- NHS. Strength exercises (last reviewed 28 February 2024). Read 2026-10-31. source
- NHS Better Health. How to lose weight. Read 2026-10-22. source
- Leidy HJ et al. The role of protein in weight loss and maintenance. Am J Clin Nutr 2015. PMID 25926512. source
- A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med 2018. PMID 28698222. source
- The effects of exercise interventions on weight regain after weight loss: a systematic review and meta-analysis. Sci Rep 2026. PMID 42331977. source
- Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts. Lancet Public Health 2022. PMID 35247352. source
- The intervention effects of resistance exercise on sarcopenia in older adults: a systematic review and meta-analysis. BMC Geriatr 2026. PMID 42304276. source
- Effects of exercise interventions on fall-related injuries in community-dwelling older adults: an updated systematic review and meta-analysis. Front Public Health 2026. PMID 42718525. source
- NHS. Physical activity guidelines for older adults (last reviewed 15 August 2024). Read 2026-10-31. source
- Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: a meta-analysis. Open Access J Sports Med 2017. PMID 29138605. source
- The impact of creatine supplementation associated with resistance training on muscular strength and lean tissue mass in older adults. Eur Rev Aging Phys Act 2025. PMID 41388441. source
- Association of efficacy of resistance exercise training with depressive symptoms: meta-analysis and meta-regression. JAMA Psychiatry 2018. PMID 29800984. source
- The effects of resistance exercise training on anxiety: a meta-analysis and meta-regression analysis of randomized controlled trials. Sports Med 2017. PMID 28819746. source
- Progressive resistance training for concomitant increases in muscle strength and bone mineral density in older adults: a systematic review and meta-analysis. Sports Med 2022. PMID 35608815. source
- Combined effects of strength training, whey protein, and HMB on sarcopenia in older people: a systematic review and meta-analysis. Medicine (Baltimore) 2026. PMID 42700006. source
- NHS. Chest pain. Read 2026-10-31. source
- NIDDK. Prescription medications to treat overweight and obesity (page last reviewed June 2024). Read 2026-10-22. source
- NHS. Overview: eating disorders. Read 2026-10-31. source
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Related goals
Lose Weight Sustainably → Maintain a Healthy Weight → Gain Weight Safely → Manage Hunger & Cravings → Build More Balanced Eating Habits → Understand Weight-Loss Plateaus → Manage Weight Changes in Midlife → Maintain Progress Over Time →
Ingredients, foods and supplements
Whey protein → Collagen and creatine → Weight-loss supplements, fat burners, detox teas and vinegar: claim check →
Research, safety and claim-check resources
BMI, body composition and muscle → Metabolism myths → Recovery after exercise → Strength training and protein for older adults → Weight and metabolism safety → Medicines that can change weight → Weight-loss medications and medical care → Weight and metabolism research and evidence →