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Sunday afternoon, a kitchen counter covered in containers: rice, chicken, eggs, oats, a food scale and a phone with a macro app open. Meal prep is as much a part of bodybuilding as the gym, from the high schooler learning to eat enough to grow to the competitor weighing every gram in the last weeks before a show. Food builds the muscle, and the supplement aisle sells a lot of promises. This page sorts out bodybuilding nutrition and supplements by the evidence: how much protein, what creatine does, the real health risks of contest dieting, the warning signs of an eating disorder, and how to pick supplements that are tested.
General information, not medical or nutrition advice. Talk to a doctor or a registered dietitian (ideally a sports dietitian) before big diet changes or new supplements, especially if you’re under 18, pregnant, take medication or have a kidney, liver or heart condition. Back to the bodybuilding hub.
Protein: how much is enough?
The International Society of Sports Nutrition (ISSN) says a daily intake of 1.4 to 2.0 grams of protein per kilogram of body weight is enough for most people who exercise to build and keep muscle. During a calorie deficit, resistance-trained people may need more, around 2.3 to 3.1 g/kg, to hold on to lean mass. Spread it out: the ISSN suggests 20 to 40 grams (about 0.25 g/kg) per meal every 3 to 4 hours, and notes the muscle-building effect of a workout lasts at least 24 hours, so there’s no need to panic about a 30-minute window. Whole foods (meat, fish, eggs, dairy, soy, beans) cover most needs; a protein powder is simply convenient. For an 80 kg (176 lb) lifter, 1.4 to 2.0 g/kg works out to about 112 to 160 grams a day.
Calories and carbs: off-season vs prep
To grow, you need a small calorie surplus and enough carbohydrate to fuel hard training; ACSM and its partners suggest roughly 3 to 7 g of carbohydrate per kilogram a day for light to moderate training loads. In contest prep, the evidence review by Helms and colleagues (2014) recommends losing about 0.5 to 1% of body weight per week to protect muscle, with 15 to 30% of calories from fat and the rest from carbohydrate. Slower is safer and keeps more muscle. Crash diets, very long preps and repeated cycles of extreme dieting carry real costs, below.
Contest prep risks and RED-S
Getting stage-lean is an extreme state for the body. In a detailed case study of a natural bodybuilder, body fat fell from about 15% to 4.5%, resting heart rate dropped to 27 beats a minute, testosterone fell to roughly a quarter of its starting level, and mood worsened sharply, before recovering in the months after the show. The International Olympic Committee calls this kind of problem REDs (Relative Energy Deficiency in Sport): when an athlete doesn’t eat enough to cover training and basic body functions, it can affect hormones, bone health, mood, immunity and performance, in men as well as women. Watch for:
- Missed or stopped periods (never “normal” for a dieting athlete), or very low sex drive in men.
- Stress fractures or bone pain, frequent illness, constant fatigue, dizziness or feeling cold all the time.
- Strength steadily falling, poor sleep, irritability or low mood.
If you notice these, talk to a doctor and a sports dietitian; a longer, gentler prep or a break from dieting may be the right call. For the dangers of drugs and peak-week dehydration, see bodybuilding injuries and health risks and our safe Show Day guide.
Eating disorders and muscle dysmorphia: the warning signs
Bodybuilding is an aesthetic sport, and the Helms review warns that competitors face a higher risk of eating and body-image disorders and should have access to mental health professionals. A 2017 meta-analysis found more symptoms of muscle dysmorphia (feeling too small or not muscular enough no matter how big you get) in bodybuilders than in other lifters, and more in competitive bodybuilders than non-competitive ones. The National Institute of Mental Health (NIMH) says eating disorders affect people of all ages, sexes and body sizes, including people who look healthy, and that they can be treated, with early help making a difference. Warning signs include:
- Rigid food rules that cause panic or guilt when broken, or eating in secret.
- Binge eating after a show or a “cheat,” followed by restricting, purging or extra cardio to make up for it.
- Constant body checking in mirrors, or never feeling lean or big enough.
- Skipping social events, work or school because of training or food, or training through injury.
- Thinking about steroids or other drugs to fix how you feel about your body.
Where to get help (US): talk to your doctor, or call the ANAD Eating Disorders Helpline at 1-888-375-7767 (free, Monday to Friday, 9 a.m. to 9 p.m. Central). If you’re in crisis or having thoughts of harming yourself, call or text 988 (Suicide & Crisis Lifeline) any time.
Creatine: the best-studied supplement
The ISSN’s position stand says creatine supplementation raises creatine stores in muscle and consistently improves high-intensity exercise performance, leading to greater training adaptations, and that short- and long-term use has been safe and well tolerated in healthy people in studies. The IOC’s supplement consensus lists creatine among the few with good evidence. Expect some weight gain from water held in the muscle (the IOC mentions 1 to 2 kg), which isn’t fat. Follow the label; there’s no need for complicated loading schemes. The American Academy of Pediatrics recommends against performance-enhancing supplements, including creatine, for young athletes, so teens should talk to their doctor first. Compare options in the best creatine.
Third-party testing: why it matters for lifters
Supplements aren’t approved by the FDA before they’re sold, and contamination is a real problem. A study of 634 supplements from 13 countries found about 15% contained undeclared prohormones (steroid precursors). Products marketed as SARMs are even worse: in a 2017 analysis of 44 products sold online, only about half contained what the label said. If you compete in a tested federation, a positive test counts against you whatever the label said. Look for NSF Certified for Sport or Informed Sport: NSF checks label claims, screens for about 290 banned substances and audits factories. Certification lowers the risk but can’t remove it entirely. Avoid anything sold as a “SARM,” “prohormone” or “test booster” with an anabolic promise, and be wary of proprietary blends and big stimulant doses in pre-workouts.
Supplements bodybuilders commonly use (all third-party certified)
Prices change often. The prices below are what we saw at the maker or a major retailer in October 2026; check the current price before you buy.
Thorne Whey Protein Isolate
- 21 g protein per serving
- 30 servings
- NSF Certified for Sport
Thorne Creatine
- 5 g per scoop
- 90 servings
- NSF Certified for Sport
Klean Athlete Klean Multivitamin
- 2 tablets per serving
- 30 servings
- NSF Certified for Sport
| Product | Per serving (label) | Certification | About price | Per serving |
|---|---|---|---|---|
| Thorne Whey Protein Isolate | 21 g protein | NSF Certified for Sport | $65 / 30 servings | about $2.17 |
| Thorne Creatine | 5 g creatine monohydrate | NSF Certified for Sport | $44 / 90 servings | about $0.49 |
| Klean Multivitamin | 2 tablets (1,000 IU vitamin D, no iron) | NSF Certified for Sport | $46 / 30 servings | about $1.53 |
A multivitamin is a backstop, not a fix for a poor diet. During long preps, some athletes run low on vitamin D or iron; get tested before taking single high-dose products. More comparisons: the best protein powder for athletes and the best multivitamin for athletes. For eating around training, see bodybuilding recovery.
Bodybuilding nutrition and supplements: FAQs
How much protein do I need to build muscle?
The ISSN says 1.4 to 2.0 g per kilogram of body weight per day is enough for most people who train, spread over meals of 20 to 40 grams. During a diet, lifters may need more (around 2.3 to 3.1 g/kg) to keep muscle.
Is creatine safe?
The ISSN position stand says creatine has been safe and well tolerated in healthy people in short- and long-term studies. Follow the label, choose a third-party-certified product and check with a doctor if you have kidney problems or take medication. Teens should ask their doctor first.
How fast should I lose weight for a show?
An evidence review of natural contest prep recommends about 0.5 to 1% of body weight per week to keep as much muscle as possible. That usually means starting prep early rather than crash dieting.
What is muscle dysmorphia?
A body-image condition in which someone believes they’re too small or not muscular enough, however big they are. Research finds more symptoms in bodybuilders, especially competitors. It’s treatable: talk to a doctor or mental health professional, or call the ANAD helpline at 1-888-375-7767.
Can a supplement make me fail a drug test?
Yes. Contaminated supplements have caused positive tests, and products marketed as SARMs or prohormones often contain banned drugs. NSF Certified for Sport or Informed Sport products lower the risk, but no product is risk-free.
Do I need supplements to build muscle?
No. Enough calories and protein from food, hard training and sleep do the heavy lifting. Protein powder and creatine are convenient and well studied, but they’re extras.