Metabolic Adaptation describes how the body fights to maintain equilibrium and prevent starvation. It was very helpful back in our caveman days but a real problem today for people who need to lose weight.
As you lose weight your body adapts to conserve energy and be more efficient. With less body weight, resting metabolic rate decreases and you do not burn as many calories when exercising. With less food intake thermogenesis lowers. Hormones increase to stimulate appetite and stress from eating too little can cause higher levels of cortisol in the body.
As metabolic adaptation occurs weight loss reaches a plateau. At this point weight loss can continue only if you add more exercise or reduce calories even more. If calorie intake is already very low and exercise volume is very high you reach a limit where it is not safe, realistic, or advisable to continue such extremes. If you stop your routine weight gain is common.
A good example of metabolic adaptation comes from research on The Biggest Loser. Researchers measured 14 participants metabolic rate at the start and end of the show. On average metabolic rate decreased by 610±483 calories. Following up 6 years later 13 of the 14 participants gained weight, although most kept at least 10% of their weight off. Metabolic rate remained low and did not go back to normal as their weight increased. Overall metabolic rate was 500 calories lower than what would be expected in people of similar height, weight, and age.
To minimize metabolic adaptation it is recommended to decrease calories gradually to support 1-2 pounds of weight loss per week rather than crash dieting for rapid weight loss. Eat protein rich foods at each meal and snack since protein has the highest thermic effect, provides satiety, and helps retain more lean muscle mass. In addition to cardio, make sure you strength train at least twice per week since lean muscle increases metabolism. Get enough sleep for the body to recover and work on stress management.
As weight loss starts to plateau make additional modest adjustments to continue losing. The ultimate goal is to develop healthy routines that are sustainable long term and help you feel energized and healthy. Understand that weight loss is not easy. We generally overestimate the amount of calories we burn and underestimate the amount of calories we consume. Work on accuracy before assuming your metabolism is damaged.
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