If you’ve ever tried to drop a good 10+ pounds, you know how hard it can be—and how it seems to get even harder as the scale starts to budge.
You’re definitely not imagining this uphill weight-loss battle. The culprit: your metabolism.
Your metabolism is a series of chemical reactions that occur inside your body to break down food and turn it into energy, says David Greuner, M.D., managing director and co-founder of NYC Surgical Associates. Your body uses this energy to perform basic functions, like keeping your lungs breathing and your heart beating, and power you throughout the day.
The minimum number of calories we need every day to keep us functioning (even if we’re at rest all day and night) is known as our basal metabolic rate. For the average person, it’s usually between 1,500 and 2,200 cals per day, says Greuner. Your individual metabolic rate is determined by your body size, sex, and age, according to the Mayo Clinic.
How many calories we need on top of that base number depends on factors like our activity level and how much muscle we have. (Muscle mass requires extra energy to maintain, so it really bumps up your metabolism.)
Related: 5 Myths About Your Metabolism
When we want to lose weight, we create a caloric deficit, meaning we try to use more calories than we consume, usually by cutting calories and exercising, explains Tyler Spraul, C.S.C.S. The goal is that our body will tap into the fat we have stored for to make up for that energy deficit.
Here’s where things get tricky, though: When most people lose weight, they tend to lose some muscle mass along with fat, says Tom Holland, C.S.C.S., exercise physiologist and author of Beat the Gym. And the less muscle you have, the fewer calories your body needs to sustain itself—which means your metabolism slows down. As this occurs, whatever caloric deficit you’d created when you first started losing weight becomes less and less effective.
So, yeah, it’s sad but true: Weight loss—especially extreme calorie-cutting—does slow down your metabolism, which actually sabotages your ability to maintain that weight loss long-term.
But that doesn’t mean you’re doomed! The solution? Take a slow-and-steady approach so that you can shed fat while keeping your metabolism revved and holding onto as much precious muscle as possible. To do that, shift your focus from cutting as many calories as possible to strength training regularly (at least three days a week) and eating ample protein—both of which support muscle mass, says Holland. He recommends eating roughly half your bodyweight in grams of protein each day. By continuing to boost your metabolism, you’ll naturally burn through more calories and make losing that fat easier.