(P32-024-23) Using a Low Carbohydrate and High Fat Diet to Alter Body Composition: A Natural Bodybuilding Case Study

Objectives: The objective of the current case study was to examine whether or not a low-carbohydrate, high-fat, high protein diet can be a useful dietary strategy for natural physique competitors, as well as other people, seeking to decrease body-fat content while maintaining muscle mass without any significant consequences to blood lipids and glucose concentrations.

Methods: A 27-year old male amateur bodybuilding competitor spent 20-weeks preparing for competition while moving through three dieting phases. Phase 1 lasted eight weeks and consisted of low carbohydrates ( < 20%), moderate fat (~35%), and high protein (~50%). Phase 2 lasted nine weeks and consisted of very low carbohydrates ( < 10%), high fat ( >60%), and moderate protein (~35%). Phase 3 lasted three weeks and consisted of very low carbohydrates ( < 10%), moderate fat (~30%), and high protein ( >60%). Fasting ( >12 hours) blood samples were collected at baseline and at the end of each phase and blood lipids and glucose levels were measured.

Results: During the overall 20-week diet alterations, total body weight decreased by -16.33% with a net loss of -1.41% in lean body mass and a -62.03% decrease in body fat. After phase 1, the subject had a 4.55% increase in fasting serum glucose along with decreases in serum total cholesterol (-22.4%), HDL cholesterol (-23.24%), LDL cholesterol (-29.7%), and triglycerides (-2.94%). After phase 2, the subject had an increase in serum total cholesterol (+83.1%), HDL cholesterol (+44.7%), and LDL cholesterol (+125.35%) with no changes in serum glucose and triglycerides. During the final phase, the competitor returned to low carbohydrate and high protein for three weeks and once again saw a decline in serum total cholesterol (-16.15%), HDL cholesterol (-14.12%), and LDL cholesterol (-18.75%). Serum triglycerides and glucose concentrations were unchanged.

Conclusions: At the conclusion of this case study, the competitor won first place in their respective open lightweight division while placing third in the open overall competition. This case study suggests that using a low carbohydrate, high fat, high protein diet can be a useful diet strategy for physique competitors in reducing body fat content with little muscle mass loss and minimal overall increases in serum total, HDL and LDL cholesterol concentrations.

Funding Sources: Self funded by PI