Ask Leyla: Which matters more—the amount or type of calories you consume?

| By Leyla Muedin MS, RD, CDN

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Young Asian woman holding a salad in one hand and rejecting potato chips with the other

Q: What difference does it make if I’m on a low-fat or low-carb diet for weight loss? Isn’t it all about the calories? Don’t I have to burn more calories than I take in?

A: It does make a difference what type of diet you’re on. We’ve known for some time that low-calorie diets, which are typically low in fat, don’t work as well as a low-carb diet. The calories in, calories out mantra of nutrition is medieval at this point. 

Fact: The type of calorie consumed determines its metabolic fate. 

For example, because of their impact on blood sugar and insulin, carbohydrate calories will tend to be stored as fat, while fat and protein calories will tend to be burned for energy. 

Having said this, however, doesn’t give us license to eat all the calories we want. At the end of the day, there is still a limit—indeed, calories do count. Should you consume 3,500 calories a day? Only if you’re an NFL linebacker. 

We’ve known for years that those who follow a low-carb diet can consume as many as 250-500 more calories per day and still lose more weight than on a low-fat diet. Another bonus: Body composition changes are more favorable on a low-carb diet. We burn more fat while lean body mass is spared. 

Unfortunately, by following a low-fat diet, we lose both muscle and fat. We want to keep as much of our lean body mass as possible, especially as we get older when conditions like sarcopenia and osteopenia/osteoporosis begin to show up. 

Another disadvantage of low-calorie dieting is that eating the same amount of calories every day will eventually slow metabolism. By letting Mother Nature know that calories are in short supply, she’ll respond by slowing metabolism or even halting weight loss altogether to make sure you survive. Weight-loss plateau, anyone? 

What happens next? The moment you stop “dieting” and eat more calories like you used to, you gain weight. But guess what? That’s supposed to happen! Nature has to fatten you up now for the next famine (read: calorie-restricted diet). This is how our metabolism works. 

Lesson: Our calorie intake should be different every day so Mother Nature doesn’t think there’s a famine going on. So stop counting calories. 

Another problem: How long are you willing to go hungry? The biggest complaint about low-calorie dieting is chronic hunger. That’s why the rate of recidivism is so high on any calorie-restricted diet. On a low-carb diet, hunger normalizes. It’s a gift! You are in ketosis (fat-burning metabolism) and the false hunger and cravings you were once plagued by are now gone. 

To your health! 

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