No matter what diet plan you choose, successful weight loss requires that you create a calorie deficit. You must burn more calories each day than you take in from food. However, the “more is better” axiom does not apply to calorie reduction. Cutting calorie intake too far can send your body into starvation mode, slowing weight loss and sacrificing much-needed muscle tissue.
Recommended Minimums
Healthy adults on a weight-loss plan should lower caloric intake to no fewer than 1,200 per day for women and 1,500 per day for men, according to the Weight-control Information Network. That represents a daily reduction of 1,000 calories from the averages for women and men. Each pound of fat equals 3,500 calories, so a reduction of 1,000 calories per day should result in the recommended safe rate of weight loss of 2 pounds per week.
Metabolic Reaction
Severe calorie restriction can induce metabolic changes as the body attempts to gain efficiencies designed to ward off starvation. The so-called starvation mode is initiated when blood sugar levels dip to below 2.2 milligrams per deciliter, or mg/dL. The body’s first responsibility is to maintain that minimum to continue healthy brain function and other critical organ and tissue functions, so it prioritizes energy conservation by converting muscle and bone tissue first.
Lean Tissue
The body can more readily convert lean muscle mass to energy in an emergency than fat stores. Converting fat requires more energy, so a body in starvation mode looks to lean mass first to maintain balance. Additionally, muscle mass requires more energy to maintain than fat does, so reductions of lean tissue lower the body’s daily calorie requirements, further slowing the metabolic process.
VLCD
Very low-calorie diets, or VLCD, must be supervised by a medical professional and prescribed for a specific obesity-related medical condition. Daily intake on a VLCD can be less than 800 calories, but the body is prevented from entering starvation mode with specially formulated meal replacements. Anyone on a VLCD should also undergo behavioral therapy and a transition period from the VLCD to a more moderate weight-loss program when weight-related health conditions have improved.
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