28 Weight Loss Myths That Pack on Pounds

The body’s only energy source is the food a person consumes. When deprived of that, the body will go to great lengths to preserve energy, according to Hirshberg. At the beginning of a deprivation people may lose some weight — water, muscle, and even fat — but after a few weeks they will gain even more back, she added. “That’s the harm people often miss — undereating is not sustainable.”

Like starving, skipping meals is not a good way to lose weight in the long-term. At first, blood sugar levels drop, making you feel tired. Then you lose water weight and muscle. Fat is stored because the body goes into a “crisis” mode, thinking it needs to preserve as much energy as possible, Hirshberg noted. Hormones that control hunger and satiety are released, setting you up for overeating later.

Not all fat is created equal, and the body needs the healthy kind — essential fatty acids — as its name suggests. You can only get these from foods such as fish, nuts, avocado, eggs, chia seeds, olive oil, and some fortified foods. Omega-3s are essential for building healthy cells. “Most people are happy to eat these foods when I explain how good they are for them,” Hirshberg said.