7 Silly Weight-Loss Myths Debunked By A Dietitian

Separating fact from fiction when it comes to popular diets (gluten-free, carb-free, fun-free) that promise quick and lasting results.
7 Silly Weight-Loss Myths Debunked By A Dietitian

Deep down, we all know how to maintain a healthy weight: eat a balanced diet, move your body, and talk to your doctor if that still doesn’t work. And yet, we keep getting suckered into fad diets that are at best ineffective, and at worst, expensive and dangerous. Here are seven common weight loss myths, debunked with the help of registered dietitian Andrea D’Ambrosio, owner of Dietetic Directions and spokesperson for Dietitians of Canada.

1. The alkaline diet

The hype: Touted by the likes of Elle Macpherson, Gwyneth Paltrow and Victoria Beckham, people swear their bloating, weight gain and general illness is caused by acidity in their blood (and for a hot second in history, it had celebs carrying urine-testing pH strips in their Balenciagas). To counter this, the diet prescribes eating alkaline foods like dark, leafy greens and cutting out acidic foods like alcohol and meat.
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The reality: “The foods we eat cannot change the pH level of our blood or body cells,” says D’Ambrosio — your blood will only be acid or alkaline if you’re seriously ill. Diet can affect the pH of your urine, but only because your body automatically maintains its own pH balance by excreting excess acid in urine. Acidic urine is not a marker of bad health, nor is it the cause of your weight gain.

2. All fat is bad for you

The hype: Fat is a dirty word, and you should avoid all types of unsaturated, saturated and trans fats at all costs, especially while trying to lose weight. The reality: Any diet that cuts something out completely is suspect. Many fats are good for you, and some aren’t associated with weight gain. Studies have shown that a high-fat Mediterranean diet, rich in olive oil and nuts, does not cause weight gain. D’Ambrosio recommends replacing saturated and trans fats, found in highly processed foods, with healthy plant-based (monounsaturated) and omega-3 (polyunsaturated) fats.

3. All carbs are bad for you

The hype: In the '90s and '00s, low-carb diets were thought to be the key to weight loss, giving even whole grains and fruits a bad rep. Unfortunately, the Atkins craze just won’t die. The reality: Carbs in the form of whole grains and fruit are an important source of energy; the problem is refined carbohydrates and white flour products found in highly-processed packaged foods. While many people do lose weight on low-carb diets, it’s largely because they’re cutting out cakes and cookies — and the results don’t tend to last. “When our carbohydrates are cut too low, our body actually resorts to breaking down our muscle before it would go to fat tissue,” explains D’Ambrosio. “When you're planning on losing weight, fibre [found] is your friend, and carbohydrates can be used strategically to ward off hunger.”

4. Crash diets can be a good idea in the short-term

The hype: Rapid and long-lasting weight loss can be achieved by combining extreme calorie-restricting diets with high-intensity exercise.
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The reality: A recent study showed that most of the contestants on the weight-loss TV show The Biggest Loser have gained back all or more of the weight they lost while on the show. Your body fights back against drastic weight loss; when you lose a ton of weight rapidly, your resting metabolism slows drastically. This means your body is no longer burning enough calories to maintain your new, thinner size for long, says D’Ambrosio. She recommends a gradual weight loss of one to two pounds week, alongside implementing lifestyle changes that are sustainable.

5. Going gluten-free helps you shed pounds

The hype: Even if you’re not gluten-sensitive, cutting gluten out of your diet will make you lose weight because you’ll be eating fewer calories. The reality: There’s no evidence that simply getting rid of gluten will result in weight loss. Gluten substitutes may actually increase calorie content by being full of fat and sugar, says D’Ambrosio. They can actually contribute to weight gain — plus you’ll be missing out on the essential B vitamins and fibre of many gluten-filled foods.

6. Eat foods that "jump-start" your metabolism to lose weight


The hype: If you’re working out and eating well but not losing weight, a slow metabolism is to blame. Foods like green tea, black coffee and spices can speed up a metabolism. The Master Cleanse diet requires you to drink a glass of water with lemon juice and cayenne pepper every morning to “jump-start” your metabolism. The reality: While there’s been some research suggesting that certain foods may slightly and temporarily increase metabolism, most experiments have been on animals and the research is far from conclusive. A little bump in metabolism won’t have a significant effect on long-term weight loss. “If you want your body to burn more calories at rest, then doing more resistance and strength-building exercises will help,” says D’Ambrosio, since muscle burns more calories than fat.

7. Eating infrequently causes weight loss

The hype: Skipping meals is an effective way to restrict calories and lose weight. The reality: Most nutritionists now recommend eating smaller, more frequent meals as the key to weight loss, since skipping meals can actually slow your metabolism. “By skipping meals, we tend to get over-hungry, and we make less healthy choices at subsequent meals,” D’Ambrosio adds.

Originally published August 2016; Updated September 2018.

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