Why youre not losing weight in a calorie deficit and how extreme diets actually slow your metabolism

Are fasting, calorie counting, and deprivation slowing your metabolism and preventing you from meeting your weight loss goals?The basic theory behind a calorie deficit is simple: Burn more calories than you consume, and your body will dip into its fat reserves for energy, leading to weight loss.Jill Brown, a certified master health coach and nutrition expert, told The Post that this concept is known in fitness circles as CICO, or “calories in vs.calories out.”But what does it mean if you’re counting calories and not getting results?Women typically need between 1,800 and 2,400 daily to maintain their weight, while men require around 2,000 to 3,000, according to the 2020–2025 Dietary Guidelines for Americans. Experts agree that weight loss happens when the body is in a calorie deficit; however, determining how many calories you consume and what equals a deficit is slippery math.

In fact, a landmark study found that people miscalculate how many calories they take in by as much as 1,000 calories a day. “When people tell me they’re in a calorie deficit, I ask them, ‘How do you know?’ They can’t really answer.  The truth is, if you’re not losing weight, you’re simply not in a calorie deficit,” said Brown.Brown explained that part of the disconnect between counting calories and losing weight is that most folks don’t know their exact resting metabolic rate or RMR.“Home smart scales are unreliable, and I see many people using this as their primary measurement,” she said.“Getting a DEXA scan that measures your body composition is your best option. The next best would be an InBody machine.

These machines will give you an estimate of your RMR, or how many calories your body burns a day doing nothing.”These machine-generated estimates are based on body weight, muscle mass, bone mass, and fat mass, providing a more accurate picture of your caloric expenditure.Brown explained that online calculators only factor in age, height, weight, an...