Although we may be drawn to the allure of rapid weight loss advertising, health expertsTrusted Source have traditionally recommended a slow-and-steady method. “Half a pound to two pounds per week is what’s universally considered a safe and sustainable,” says Jessica Crandall Snyder, registered dietitian and spokeswoman for the Academy of Nutrition and Dietetics.
So, what happens if those programs really do follow through with their “overnight” promise? “Losing weight too quickly, especially through starvation techniques, can result in a number of side effects, some more downright dangerous than others,” says registered dietitian and Trifecta Nutrition Director Emmie Satrazemis, CSSD.
1. You Could Be Missing Out On Important Nutrients
“Many quick diets and eating plans cut out whole food groups, which means you could be missing out on key nutrients, vitamins, and minerals that you need to stay healthy,” says Bonnie Taub-Dix, registered dietitian nutritionist, spokesperson for the California Avocado Commission, and author of “Read It Before You Eat It — Taking You from Label to Table.” Snyder brings up how a dairy-free diet could result in a calcium deficiency while a diet that cuts carbs could mean you’re not getting enough fiber. Even on a lower-calorie diet, it’s important to get a range of nutrients including calcium, vitamin D, vitamin B-12, folate, and iron.
2. Your Metabolism Can Get Slower
Rapid weight loss usually occurs from extreme calorie deprivation, for example, people who go from eating 3,000 to 1,200 calories a day, says Gans. Trouble is, our body recognizes this as a sign of limited food supply and goes into starvation mode. Kristina Alai, a personal trainer at The Bay Club Company, highlights the trouble with this: “When your body goes into starvation mode, your metabolism will slow down to help you conserve energy and your body will hang onto more fat.”
3. You Might Be Losing Muscle, Instead Of Fat
“When we lose weight, we want to get rid of true adipose tissue. Not muscle mass. I’ve never met someone who complained about having a higher percentage of body muscle,” says Snyder. But if you cut calories too quickly, muscle tone will seriously suffer. “Calorie restrictive diets may cause your body to break down the muscle for energy and fuel,” says Satrazemis. In addition to waving goodbye to your shapely guns and rear, a loss in muscle mass can slow your metabolism.
4. You Could Become Really Dehydrated
Thanks to water weight, it’s common to see slightly faster weight loss in the first two weeks. “Especially on low-carb or no-carb diets, folks will lose a lot of water weight,” says Taub-Dix. According to her, it’s one the reasons the ketogenic diet is often praised for quick weight loss. Trouble is, rapid water loss can lead to dehydration and a host of unpleasant side effects like constipation, headache, muscle cramps, and low energy.
5. You Could Feel Ravenous
When you go on quick-fix, low-cal diets, your levels of leptin — the hormone that controls hunger and satiety — get wonky, says Taub-Dix. When leptin levels are normal, it tells your brain when your body has enough fat, which signals the brain that you’re full. But researchTrusted Source has found that on very-low-calorie diets, unbalanced leptin levels can result in an obsession with food. You may be more ravenous, hangry, and likely to binge.