Adaptations of Exercise Energy Metabolism in Response to Weight Loss in Healthy Normal Weight People

More and more normal weight people are dieting in the general population. The NUTRILEX study aims to better understand the physiological adaptations in response to weight loss in healthy normal weight individuals. After an inclusion visit to verify the eligibility criteria of the subjects, they will complete a "T0" control session. The subjects will then have to complete two phases. The first transversal phase consists of 4 randomized sessions with lunch ad libitum after a physical exercise: i) a control session (no exercise, CON); ii) an exercise session at initial body weight (BWT0); iii) an exercise session with a simulated weight loss of 3% performed on an anti-gravity treadmill (BW-3%) and; iv) an exercise session with a simulated weight loss of 6% performed on an anti-gravity treadmill (BW-6%). During the second longitudinal phase, the participants will perform a dietary rebalancing and a slight caloric restriction (dietary intervention) in order to induce a weight loss of 6% of their initial body weight. Subjects will then perform an exercise session after losing 3% (T1) and then 6% (T2) of their initial body weight.

Inclusion Criteria: * Body mass index (BMI) between 18.5 and 24.9 kg/m², * Subjects abled to understand the information note and abled to sign the consent form, * Subjects with stable body weight (variation \< 3% of body weight) until at least 6 months, * Subjects subjected to a social security plan. Non-Criteria: * Have achieved a minimal BMI \< 18.5 or maximal BMI ≥ 25 kg/m² in adult life, * Subjects with high levels of physical activity (\> 5 h of exercise per week), * Presence of comorbidities or medical conditions that may interfere with study data, * Subjects undergoing energy restriction or physical activity weight loss program at the time of inclusion or within the past 6 months, * Taking medication that may interfere with study results, * Surgery within the last 3 months, * Person under guardianship, curatorship, or safeguard of justice; or not subject to a social security plan, * Pregnant or breastfeeding women, * Refusal to sign the consent form, * Person in a period of exclusion from another study, * Regular consumption of tobacco or alcohol, * Voluntary weight loss in the last 6 months, * Present or past eating disorders.