A Nutrition Guide for Bodybuilding Competition Prep

Female weight lifting with barbell

Getty Images / Willie B. Thomas

Competitive natural bodybuilding is growing in popularity and lacking adequate scientific research. Without relevant information for participants, they are at a loss using contest prep guesswork. Even worse is relying on inaccurate feedback from buddies and coaches.

Recent research has addressed this issue. Several authors were assigned a specific subject of their expertise and have provided evidence-based findings established on carefully screened scientific publications. The team narrowed the scope of the narrative to “calories and macronutrients, nutrient timing and meal frequency, dietary supplementation, psychosocial issues and “peak week.”

The ongoing problem for many competitors is lacking knowledge so they follow a “one-size-fits-all” nutrition and supplement program. This leaves many bodybuilders unable to reach their goals and struggling with reasons why.

Following a “one-size-fits-all” nutrition and supplement program leaves many bodybuilders unable to reach their goals and struggling with reasons why.

The evidence-based guide recently published by the Journal of the International Society of Sports Nutrition has shed some light on the very important phase of contest prep: nutrition and supplementation. The narrative is very informative and a great read. This article simplifies the narrative, beginning with nutrition and recommendations for macronutrients.

Caloric Intake

Typically, contest preparation follows a minimum of 2- to a 4-month diet plan. The primary goals are shredding fat and increasing muscle size before hitting the stage. Each person begins at different body fat percent and muscle size. Being able to accurately balance the macronutrients specific to the changing needs of the participant through the training process is essential.

This is where it becomes tricky due to a lack of specific research for natural bodybuilders. Research indicates, “it should be expected that the caloric intake at which one begins their preparation will likely need to be adjusted over time as body mass decreases and metabolic adaptation occurs.”

Losing weight too fast can lead to loss of lean body mass (LBM) and strength. What has shown superior for retaining LBM is a gradual loss of .5kg or 1.1lbs per week (approximately a 500 calorie deficit per day). This figure is based on a 154lb participant at 13% body fat and no more than 15lbs over their contest weight and given a 3-month prep time. 

This means a competitor who is over the suggested weight and body fat would require faster weight loss methods and risk losing lean body mass (LBM). Ample time should be allowed to prepare for competition. This helps prevent aggressive weight loss measures linked to decreased LBM. Also, the program length needs to be specific for each competitor body type.

Shorter diet periods for leaner participants compared to those with higher body fat percentages for example. A 12-week study of male bodybuilders revealed significant weight loss during the final 3-weeks of contest prep. This resulted in a loss of lean body mass (LBM).

If weight loss is needed, faster loss at the start and more gradual weight loss during the end of contest preparation period will help to maintain lean body mass.


Protein requirements are important for contest-prep and to help competitors maintain their lean body mass (LBM) or muscle. Research guidelines indicate 1.2 to 2.2g/kg of body weight is sufficient for certain athletes. Some bodybuilders may require more due to extreme training and caloric deficit conditions.

Many research publications noted the importance of a positive nitrogen balance. Also indicated is extreme exercise adversely affecting that chemical element. Nitrogen is a chemical compound naturally occurring in our bodies, primarily in proteins and essential for life.

Negative nitrogen readings are linked to muscle wasting disease, injuries and periods of fasting. Increased protein will enable the competitor to maintain a positive nitrogen balance allowing for muscle growth and repair.

A systematic review on protein intakes in resistance-trained, lean athletes during caloric restriction, by Helms et al, suggests a range of 2.3-3.1 g/kg of LBM may be more appropriate for bodybuilding.

Many studies on protein requirements and athletes have been conducted. More specific research on contest-prep and bodybuilding are warranted due to the wide variables specific to each sport.


Carbohydrates provide the energy for bodybuilders to get through their contest-prep workouts. However, carb requirements can differ for each participant. Inadequate carb intake will impair resistance training while consuming the right amount of carbohydrate will enhance performance.

Recent studies indicate consuming carbs at a value of 4 to 7g/kg of body weight and depending on the phase of training is beneficial. However, it was also reported contest-prep bodybuilders in caloric deficit need to meet protein and fat requirements. This could interfere with their ability to be at the high end of carb intake.

Overall, this information does provide a good range to start and ensure adequate carbohydrate intake during contest-prep. As competitors reach their goal weight and body fat percent, it's suggested as a worthwhile strategy to maintain caloric deficits by increasing carbohydrates by 25 to 50g. This would help preserve lean muscle and athletic performance.

Lower carbohydrate and higher protein intake can provide effective weight loss results for bodybuilders. However, research indicates a restrictive carb threshold exists where reducing them further would put the competitor at risk for lean body mass (LBM) loss and reduced performance.

Competitors who are at their leanest condition may have unavoidable drops in performance. Researchers suggest increasing carbs during the final weeks of contest prep may prevent the negative hormonal and metabolic shifts that reduce a competitor’s lean body mass.


Lean protein and carbs have always been the primary macronutrients of concern for contest-prep bodybuilders compared to fat. The importance of appropriate fat intake can no longer be denied as just as crucial.

Adequate fat intake is linked to regulating anabolic hormone concentrations. Research suggests fat intake having a direct impact on lean body mass (LBM) during the dieting phase. The argument exists “for fat intakes between 20 to 30% of calories have been made to optimize testosterone levels in strength athletes.”

Given protein and carbohydrate requirements, some research suggests these percentages may be too high. Other studies have shed light on body composition and a caloric deficit is the main problem with reduced testosterone levels and not reduced ​fat intake alone.

“In direct studies of resistance trained athletes undergoing calorically restricted high protein diets, low-fat interventions that maintain carbohydrate levels appear to be more effective at preventing LBM loss than lower carbohydrate, higher fat approaches.”

As long as adequate carbohydrate and protein levels are maintained, fat recommendations of 15-20% are appropriate.

Research Wants You to Know

More long-term studies are required for natural bodybuilding and preparing for competition. Muscle dysmorphia (not being satisfied with body image) and eating disorders are common in bodybuilders and early awareness is important to avoid adverse health issues.

Irregular periods or cessation of menstrual cycles can be an issue for female bodybuilders. Contest prep is an individual sport and each body will respond differently to diet application. Although the recommendations have been provided, manipulation of the nutrition guidelines may be necessary.

5 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementationJ Int Soc Sports Nutr. 2014;11:20. doi:10.1186/1550-2783-11-20

  2. Turocy PS, DePalma BF, Horswill CA, et al. National Athletic Trainers' Association Position Statement: Safe Weight Loss and Maintenance Practices in Sport and Exercise. J Athl Train. 2011;46(3):322-336. doi:10.4085/1062-6050-46.3.322

  3. Chappell AJ, Simper T, Barker ME. Nutritional strategies of high level natural bodybuilders during competition preparation. J Int Soc Sports Nutr. 2018;15:4. doi:10.1186/s12970-018-0209-z

  4. Hulmi JJ, Isola V, Suonpää M, et al. The Effects of Intensive Weight Reduction on Body Composition and Serum Hormones in Female Fitness Competitors. Front Physiol. 2017;7:689. doi:10.3389/fphys.2016.00689

  5. Halliday TM, Loenneke JP, Davy BM. Dietary Intake, Body Composition, and Menstrual Cycle Changes during Competition Preparation and Recovery in a Drug-Free Figure Competitor: A Case Study. Nutrients. 2016;8(11):740. doi:10.3390/nu8110740

By Darla Leal
Darla Leal is a Master Fitness Trainer, freelance writer, and the creator of Stay Healthy Fitness, where she embraces a "fit-over-55" lifestyle.