COVID-19: Click here for the latest updates and vaccine news

×
15th October, 20206 min read

Fitness supplements — the facts

Fitness supplements — the facts
Medical reviewer: Healthily's medical team
Author: Alex Bussey
Last reviewed: 16/10/2020
Medically reviewed

All of Healthily's articles undergo medical safety checks to verify that the information is medically safe. View more details in our editorial policy

Fitness supplements have been popular for some time, with people often taking them in hope of building muscle or losing weight.

You might see them on the shelves of your local supermarket, the fitness section of a pharmacy or a health shop. But do they actually work?

Evidence suggests that they may help with some types of exercise, but experts warn that they’re not always a good substitute for a balanced diet. They can also have serious side effects.

Here’s everything you need to know about fitness supplements.

What are fitness supplements?

There are 2 main types of fitness supplement and they're used for either protein boosts or weight loss.

Protein supplements

These are normally powders, bars, shakes or gels that are supposed to provide your body with large amounts of protein.

Some people believe that protein supplements make it easier to build muscle, increase your strength, control your appetite or boost your energy levels.

Weight loss supplements

These are supposed to help you lose weight by stopping your body from absorbing fat, or by speeding up your metabolism so that you can lose weight more quickly.

Some weight loss supplements also claim to suppress your appetite or make you feel full for longer to help you to lose weight without changing your diet.

But there isn’t much evidence to support these claims and some fitness supplements could be dangerous.

man in his kitchen, putting the lid on a protein shake

Do fitness supplements work?

It’s hard to say whether fitness supplements are helpful. Some athletes could benefit from a regular protein supplement — particularly if they’re doing a lot of resistance training, or struggling to get enough protein from their diet.

But experts say most people should focus on eating a balanced and healthy diet instead.

There’s also little or no evidence to support the use of weight loss supplements.

Protein supplements

Protein supplements provide large amounts of protein — an essential nutrient that’s used to build new muscle and repair some of the muscle tissue that’s normally damaged during exercise.

But most people get more than enough protein from their diet.

The British Nutrition Foundation says that you should aim to eat about 0.75g of protein per kilogram of bodyweight every day. That’s about 56g of protein for the average man and 45g of protein for the average woman.

And most people eat about 68g of protein a day, with any extra protein then burned to provide energy. So there’s usually no need to take a protein supplement unless a doctor or dietitian has advised you to, for example if you’re a professional athlete.

Athletes burn more energy than the average person. They also do more damage to their muscles, and eating more protein helps to repair some of this damage.

Female athlete jumping over hurdles

Groups like the International Society of Sports Nutrition (ISSN) say that professional athletes should aim to eat about 1.4 to 2.0 grams of protein per kg of body weight — more than double the normal recommendation.

Taking a high-quality protein supplement can help with this — particularly if you don’t have time for a meal or a snack.

But some experts warn that protein supplements aren’t always a healthy choice. They often lack the vitamins and minerals that are found in more complex food and groups like the British Dietetic Association say that it may be better to focus on eating foods that are naturally high in protein.

These include:

  • lean red meat like beef, lamb or pork
  • eggs
  • dairy produce
  • poultry
  • beans
  • tofu
  • lentils and chickpeas
  • nuts and seeds

close up of someone frying an egg in a pan

Weight loss supplements

Weight loss supplements often contain ingredients like caffeine, raspberry ketones (a natural chemical found in red raspberries) or green tea. These ingredients are supposed to stop your body from absorbing fats, reduce your appetite or speed up your metabolism.

But there isn’t much evidence to support these ideas. This is partly because the companies that make weight loss supplements don’t always carry out studies on people to make sure that their products work.

The US-based Office of Dietary Supplements (ODS) also notes that when studies are carried out, they're often too small or poorly-designed to tell us anything useful.

If you’re trying to lose weight, it’s best to focus on methods that are proven to work. This includes things like getting plenty of exercise or making long-term changes to your diet.

You could also try talking to a doctor if you’re struggling to lose weight. They may be able to give you some additional support.

woman popping weight loss pills out of a blister pack

Are fitness supplements safe?

Protein supplements can be bought without a prescription, but that doesn't mean that they’re safe to take.

These supplements aren't tested as rigorously as other medications and research shows that up to 5% of fitness supplements could contain anabolic steroids and other unlabelled ingredients. Steroids can lead to many physical problems, including high blood pressure, liver damage, stroke or heart attack. They can also cause mania and delusions.

Some weight loss supplements also contain illegal or dangerous ingredients — including things like 2,4-Dinitrophenol (DNP). This ingredient is an industrial chemical that speeds up your metabolism. It’s highly toxic and has been linked to at least 3 deaths. DNP has been banned as a weight loss drug in the USA, and in the UK it has been labelled a hazardous chemical.

Weight loss supplements can also interfere with other drugs and may have serious side effects. Before you take any supplements, you should always check with your doctor to make sure it's safe for you to do so.

Experts further warn that eating too much protein could increase your risk of osteoporosis and make some kidney problems worse. To avoid these side effects, avoid eating more than twice the recommended amount of protein.

But always talk to a doctor before you start taking a protein supplement.

Key points

  • there are 2 main types of fitness supplement: protein and weight loss supplements
  • protein supplements may be helpful if you’re training 2 to 3 times a day but most people get enough protein from their diet
  • talk to a doctor before you start taking a protein supplement
  • there isn’t much evidence to support weight loss supplements
  • talk to your doctor if you’re worried about your weight or think you need to lose weight

Bodybuilding and sports supplements: the facts [Internet]. nhs.uk. 2020 [cited 12 October 2020]. Available here.

Ruano J, Teixeira V. Prevalence of dietary supplement use by gym members in Portugal and associated factors. 2020. Available here.

Office of Dietary Supplements - Dietary Supplements for Exercise and Athletic Performance [Internet]. Ods.od.nih.gov. 2020 [cited 12 October 2020]. Available here.

Office of Dietary Supplements - Dietary Supplements for Weight Loss [Internet]. Ods.od.nih.gov. 2020 [cited 12 October 2020]. Available here.

Jäger R, Kerksick C, Campbell B, Cribb P, Wells S, Skwiat T et al. International Society of Sports Nutrition Position Stand: protein and exercise. 2020. Available here.

Protein: What you need to know [Internet]. Bhf.org.uk. 2020 [cited 12 October 2020]. Available here.

Protein [Internet]. Betterhealth.vic.gov.au. 2020 [cited 12 October 2020]. Available here.

Protein - how much should we eat? [Internet]. 2020 [cited 12 October 2020]. Available here.

Protein intake for muscle maintenance. [Internet]. Acsm.org. 2020 [cited 12 October 2020]. Available here.

Protein and the Athlete - How Much Do You Need? [Internet]. Eatright.org. 2020 [cited 12 October 2020]. Available here.

People Are Eating More Protein than They Need—Especially in Wealthy Regions [Internet]. World Resources Institute. 2020 [cited 12 October 2020]. Available here.

Sport and exercise [Internet]. Bda.uk.com. 2020 [cited 12 October 2020]. Available here.

Morton R, Murphy K, McKellar S, Schoenfeld B, Henselmans M, Helms E et al. 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. 2020. Available here.

Effects of Protein Supplementation on Performance and Recovery in Resistance and Endurance Training. Home - PMC - NCBI [Internet]. Ncbi.nlm.nih.gov. 2020 [cited 12 October 2020]. Available here.

Jurgens T, Whelan A, Killian L, Doucette S, Kirk S, Foy E. Green tea for weight loss and weight maintenance in overweight or obese adults. 2020. Available here.

A Meta-Analysis on Randomised Controlled Clinical Trials Evaluating the Effect of the Dietary Supplement Chitosan on Weight Loss. Home - PMC - NCBI [Internet]. Ncbi.nlm.nih.gov. 2020 [cited 12 October 2020]. Available here.

Tainted Body Building Products [Internet]. U.S. Food and Drug Administration. 2020 [cited 12 October 2020]. Available here.

Cooper E, McGrath K, Li X, Heather A. Androgen Bioassay for the Detection of Nonlabeled Androgenic Compounds in Nutritional Supplements. 2020. Available here.

What are the side effects of anabolic steroid misuse? | National Institute on Drug Abuse [Internet]. National Institute on Drug Abuse. 2020 [cited 12 October 2020]. Available here.

Start losing weight [Internet]. nhs.uk. 2020 [cited 12 October 2020]. Available here.

How your GP can help you lose weight [Internet]. nhs.uk. 2020 [cited 12 October 2020]. Available here.

Protein foods. [Internet]. Betterhealth.vic.gov.au. 2020 [cited 12 October 2020]. Available here.

Was this article helpful?

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.

What to read next
Supplements for menopause symptoms – do they work?

Supplements for menopause symptoms – do they work?

If you’re struggling with menopause symptoms, you might be considering trying a menopause supplement. But do they work? Discover the facts here.
Zinc foods: what to eat

Zinc foods: what to eat

Do you know what you should be eating to get enough zinc? Find out about zinc-rich foods, how much zinc you need and when to consider zinc supplements...
Magnesium supplements: benefits and side effects

Magnesium supplements: benefits and side effects

Magnesium supplements are popular, but do you need them and are they safe? Find out what magnesium does, whether you’re getting enough – and if you ca...