When it comes to losing weight and maintaining weight loss, diets are obviously a popular choice — but what kind of effect can loss (and, realistically, gaining some back) have on your metabolism?
Understanding how the metabolism works — and the changes that occur when weight fluctuates — can be useful for creating a diet that’s beneficial instead of damaging.
At a basic level, “metabolism” refers to the multiple chemical reactions that occur within the body, especially the ability to convert food into energy in the form of calories, according to Dr. Nancy Rahnama, a bariatric physician and internist in Beverly Hills, California.
“When the metabolism is high, the body will need more energy in the form of calories to sustain itself, allowing for a greater caloric intake and also making it easier to lose weight,” she says. “When your metabolism is low, you’d need to make a greater deficit in calorie intake in order to have weight loss.”
The greatest component of your total metabolism is your resting metabolic rate (RMR) — the amount of calories needed to fuel the body’s essential functions, such as digestion, breathing and heart pumping. Your rate is greatly influenced by your age, muscle mass and total weight. Lesser factors, but still important, that affect the metabolic rate are genetics, hormone levels and vitamin levels, as well as increases in physical activity.
For example, someone with lower muscle mass who’s sedentary will have a slower metabolism than someone with healthy muscle mass who exercises regularly.
Research on weight loss — particularly on dramatic calorie cutting — suggests the body lowers metabolism when you diet, in an effort to maintain a “set point,” says Dr. Nicole Harkin, attending cardiologist at Manhattan Cardiovascular Associates.
“This downregulation of the basal metabolic rate, known as adaptive thermogenesis, can persist for some time, with recent research indicating it can last for years,” she notes. “We don’t yet know what exactly determines that set point, and more importantly, how to reset it.”
She adds that some studies suggest building lean body mass may help to attenuate this and support a higher metabolic rate. She also emphasizes that weight loss isn’t only about metabolism, but can also be affected by hormonal changes, genetics, environment and even gut microbiota. Just because your metabolism may have slowed, you shouldn’t ditch healthier eating and give up.
DROP THE YO-YO
One of the most challenging strategies for the metabolism is yo-yo dieting, in which someone loses and regains weight regularly, sometimes within short timeframes.
When you fall off a diet and start eating more — sometimes quite a lot more — your metabolism doesn’t just bounce back to where it was before, according to Candice Seti, PhD, licensed clinical psychologist, certified personal trainer and certified nutrition coach, who’s known as The Weight Loss Therapist.
Depending on other factors, such as age and gender, your metabolism may stay sluggish, and the more you yo-yo, the more damaging it can become.
“That’s why the weight you lost is much easier to regain and even harder to lose again,” says Seti. “This cycle only gets worse the longer you continue to be an on-again, off-again dieter.”
Yo-yo dieting can also cause hormonal changes that exacerbate the problem, she adds. The hormones that manage stress and hunger can get out of whack from frequent dieting. This can heighten your appetite and also convince your body to hold on to fat in case of another round of “starvation mode.” More hunger and less fat loss blends with slow metabolic function, making it likely that each new diet attempt feels harder than the one before (nope, it’s not just you!).
So, can you actually damage your metabolism by dieting? To some degree, the answer is yes, because you may be keeping it down regulated and slowed. Although research has yet to yield the magic secret for a metabolism speed-up, there are a few things you can do to begin reversing the damage.
Controlling calorie consumption is important for steady and sustainable weight loss, but it’s far from the only strategy if you want to keep your metabolism happy. Consider adding these tips to your plan:
- Get plenty of sleep: Sleep deprivation or irregular sleep patterns have been linked to weight gain risk, including more snacking, increased craving, less willpower, increased stress, lower insulin sensitivity. Seti notes that it can all add up to a more sluggish metabolism and less fat burning.
- Cool it down at night: Studies have suggested that sleeping in a colder room — about 66ºF or lower — can boost metabolism by increasing “brown fat.” This is the kind of fat you want, says Seti, since it’s the type that attacks the visceral fat that’s often in the midsection.
- Eat more protein: Containing the amino acids that support muscle mass, protein can be highly effective for keeping the metabolism going strong, says Dr. Rahnama.
- Go spicy: Eating zesty foods can have a big impact on metabolism and its fat-burning effect, according to Seti. Spicy foods can boost metabolism for hours, she says.
- Do HIIT workouts: High-intensity interval training stimulates human growth hormone production, which burns more calories, Seti says. Also, these workouts create an oxygen shortage in the body known as excess post-exercise oxygen consumption (EPOC). She notes, “This creates a monstrous metabolic boost for your body 24–48 hours post-exercise. EPOC is one of the main reasons HIIT helps you burn so much more fat than simple steady-state cardio.”
Dieting has its place for weight loss, but it has to be done in a way that supports the metabolism and keeps the body fueled. Instead of simply cutting calories — although that’s helpful to some degree — make sure to support muscle mass, exercise in beneficial ways and build in rest days. That makes it easier to drop the yo-yo and keep your weight where you want it.