Role of Peanuts in Healthy Weight Gain in Athletic Individuals (mGAINS)

Many athletes and military personnel desire weight gain primarily as lean mass to improve performance and effectiveness in military/sport endeavors. While much is known about the energy restriction required to reduce body weight, very little is understood about energy and macronutrients needed to promote healthy gains in body weight and lean mass. Typically, athletes are encouraged to increase calorie intake by ~500 kcal/day with an emphasis on adequate protein and carbohydrate, and judicious inclusion of healthy fat-containing calorically-dense foods, including peanuts and peanut butter. This study proposes to evaluate the effect of a 10-week diet and exercise regimen designed to promote healthy weight gain. This will include increasing energy intake by 500 additional kcal/day (above weight maintenance diet) through daily provision of either peanut-based whole foods/snacks (peanut group) or a similar, high-carbohydrate, peanut-free snack (control group) along with a supervised strength training regimen. Results will serve as an important first step in helping understand the gaps in knowledge related to healthy weight gain, designing better weight gain meal plans, not only in athletes and military personnel, but also in clinical populations where promotion of weight gain is advocated.

Both the investigators and participants are aware of the group assignment since the foods prepared and provided (peanut-containing or no peanut snacks) cannot be masked.

Participants will be provided and consume an extra 500 kcal/day of peanut-containing snacks for 10 weeks.

Participants will be provided and consume an extra 500 kcal/day of snacks without peanuts or peanut-containing foods for 10 weeks.

Participants will undergo a 10-week diet and weight training regimen to promote healthy weight gain. These participants will receive seven 500 kcal peanut-containing (whole peanuts or peanut butter) snacks each week and consume one snack per day throughout the study. They will also perform a series of weight training exercises supervised by a personal trainer on 3 days per week.

Participants will undergo a 10-week diet and weight training regimen to promote healthy weight gain. These participants will receive seven 500 kcal non-peanut-containing high carbohydrate snacks each week and consume one snack per day throughout the study. They will also perform a series of weight training exercises supervised by a personal trainer on 3 days per week.

Participants will be weighed on a digital scale wearing standardized lab clothes at all scheduled testing sessions throughout the study.

Participants will undergo a dual-energy x-ray absorptiometry scan wearing standardized lab clothing at all scheduled testing sessions throughout the study. The scan analysis provides body composition results, including lean (fat-free) mass to the closest gram.

Participants will undergo a resting metabolic rate (RMR) test during select testing sessions throughout the study. The indirect calorimetry test measures the daily energy expenditure (or number of kilocalories needed to perform and maintain daily bodily functions) of each participant based on the measured gas exchange during the test.

Participants will have their blood collected by venipuncture in aseptic conditions. Testosterone (free and total) will be measured to determine the impact of the extra daily 500 kcal snacks on anabolism and muscle growth.

Participants will have their blood collected by venipuncture in aseptic conditions. Insulin-like growth factor (IGF) will be measured to determine the impact of the extra daily 500 kcal snacks on anabolism and muscle growth.

Inclusion Criteria: Interested in gaining 5 pounds of body weight to enhance effectiveness in sport, fitness, or military training/competition. Willing to eat 500 kcal/d and weight train 3x/wk for 10 weeks Have weight trained in the past 12 months Not taking medications or dietary supplements that influence study results Non-smoker Without any major medical problems (including high blood pressure or coronary heart disease) Exclusion Criteria: Nut, peanut, tree nut or legume allergy No weight training experience Orthopedic limitations that affect ability to weight train Currently taking dietary supplements or prescribed pharmacological agents that may affect lean tissue accretion Current or past anabolic steroid use Have a history of or current signs of disordered eating Pregnant Abnormal levels of thyroid stimulating hormone or hemoglobin, serum lipids (e.g., fasting triglycerides >150 mg/dL and/or total cholesterol >200 mg/dL)