Adaptive thermogenesis: When you consume too few calories, your body enters a state of energy conservation, slowing down metabolic processes to preserve energy. This reduction in metabolic rate is known as adaptive thermogenesis, making it harder to lose weight.

Muscle loss: A severe caloric deficit combined with excessive aerobic activity can lead to muscle loss, as the body starts breaking down muscle tissue for energy. Since muscle tissue is more metabolically active than fat, losing muscle reduces your metabolic rate.

Hormonal changes: Prolonged caloric restriction and excessive aerobic exercise can cause hormonal imbalances, such as reduced levels of thyroid hormones and leptin, which play crucial roles in regulating metabolism and energy expenditure.

Slowed physical activity: In response to a significant caloric deficit, the body may reduce spontaneous movement and non-exercise activity thermogenesis (NEAT), further decreasing overall energy expenditure.

Energy conservation mode: As the body tries to conserve energy in response to a caloric deficit and excessive aerobic activity, it may prioritize fat storage when you eventually consume more calories, leading to increased fat gain.

To avoid these negative effects, it’s essential to maintain a balanced diet with adequate caloric intake and engage in a combination of resistance and aerobic training to support a healthy metabolism and body composition.