Weight loss, dietary carbohydrate modifications, and high intensity, physical performance

Area of Science:

• Exercise Physiology
• Sports Nutrition
• Metabolic Studies

Background:

• Maintaining physical performance during weight loss is crucial for athletes.
• Hypocaloric diets are often used for weight management, but their impact on performance varies.
• Dietary composition, particularly carbohydrate intake, may influence physiological responses to exercise during weight loss.

Purpose of the Study:

• To investigate the effects of high-carbohydrate (HC) versus low-carbohydrate (LC) diets on physical performance after 6% body weight loss.
• To assess physiological and mood state changes associated with these dietary interventions during weight loss.
• To determine if a high-carbohydrate diet can preserve physical performance during a hypocaloric weight loss period.

Main Methods:

• 12 trained subjects underwent a 4-day weight loss period (approx. 6% body weight).
• A crossover design was employed, with subjects assigned to either HC or LC diets.
• Physical performance (arm cranking), body weight, skinfolds, mood states (POMS), and blood markers (lactate, pH) were measured pre- and post-weight loss.

Main Results:

• Sprint work was maintained with the HC diet but decreased significantly with the LC diet post-weight loss.
• Post-exercise lactate levels were lower after weight loss, irrespective of diet.
• Mood states showed significant negative changes (increased tension, fatigue; decreased vigor) post-weight loss on both diets.

Conclusions:

• A high-carbohydrate, hypocaloric diet appears more effective in maintaining high-intensity exercise performance during short-term weight loss compared to a low-carbohydrate diet.
• Weight loss, regardless of diet composition, negatively impacts mood states in trained individuals.
• Further research is needed to explore long-term effects and optimal dietary strategies for athletes undergoing weight reduction.