"Building muscle is what keeps your metabolism up and helps prevent weight regain, so it's absolutely key for weight loss," Berkow told POPSUGAR, further explaining that muscle burns more calories than fat, so the more muscle you have, the more calories you'll burn at rest. Dieting and not focusing on muscle may make you regain the weight once you begin to eat more since your metabolic rate will have slowed.
Preserving your muscle mass is also important if your goal is to lose weight, because when you're in a caloric deficit — which is essential for weight loss — "your body senses that it's getting less fuel, and it slows down the number of calories it burns," Berkow said. This slows down your metabolism in order to conserve energy, a phenomenon also known as starvation mode. Strength training and eating enough protein daily are key to keep your metabolism up so you can therefore lose weight, Berkow said. As she mentioned before, you can't build a huge amount of muscle while trying to lose weight since you need those extra calories, but you can still get toned.