Can You Gain Weight If You Don't Eat Enough? 3 Experts Explain "Starvation Mode"

Starvation mode is a survival mechanism that your body triggers to halt or slow weight loss in times of low caloric consumption, said Holly Lofton, MD, director of the medical weight management program at NYU Langone Health. "You will still lose weight, but your body will become more conservative of letting go of those calories, so your metabolism decreases," Dr. Lofton told POPSUGAR. Eventually, your metabolic rate slows down so much that your calorie consumption, low as it might be, might match it. When those two equal out, you'll hit a plateau and your weight loss will stop. At the same time, Dr. Lofton explained, "your body creates a hormonal drive to increase your food intake." In other words, you get hungrier and hungrier, making it even more difficult to maintain the low-calorie diet.

Biologically, there are a few factors that go into this. Losing weight in general causes you to burn fewer calories and results in weight loss slowing down over time. That's due to strong reactions from your hormones and nervous system, which have adapted to oppose weight loss and the maintenance of weight reduction.

There's also the fact that weight loss, especially extreme weight loss that could result from starvation mode, starts to eat into your muscle tissue. When you take away the body's preferred fuel, glucose (which you typically get from carbs), your body will start looking for any other available source, said Kristin Kirkpatrick, a registered dietitian with Cleveland Clinic Wellness. The first substitutes are fats (which is the basic theory behind the ketogenic diet). If fats aren't available, that's when your body turns to muscle tissue, breaking it down to get at amino acids, which are converted to glucose by your liver and then used as fuel. It's a process called gluconeogenesis, which occurs during times of starvation, Kirkpatrick explained.

The more muscle mass you have, the faster your metabolism is. It goes the opposite way, too; if you start to lose muscle mass, your metabolism will slow down, explained registered dietitian nutritionist Megan Casper, MS, CDN. That only exacerbates your body's resistance to weight loss in starvation mode.

Starvation mode occurs at different levels of caloric intake depending on your body. On average, Dr. Lofton said, people tend to hit it when they're consuming less than 1,000 calories per day, but again, that could fluctuate up and down depending on the individual.

It's also believed the starvation mode only occurs after prolonged, extremely low-calorie dieting, Casper told POPSUGAR. "That being said, every body is different," she added. "I've had many clients who have complained after a long, low-calorie diet that weight stopped dropping and then inched back up on the scale."

It's unlikely that you're in serious risk of entering starvation mode unless you're truly not eating anything at all, Kirkpatrick said; as in, you don't have access to food or you're dealing with an eating disorder, such as anorexia. "The body can resist weight loss for many reasons, some which may have nothing to do with food," including age, hormones, and genetics, she told POPSUGAR. If you're struggling with a weight loss plateau, it's best to visit a doctor or dietitian to explore the causes that could be behind it.

If you're doing intermittent fasting, starvation mode probably isn't a major threat, Kirkpatrick said. "Fasting and starvation are completely different," she reminded us. When you fast, you might go hours or even days without food. However, you're still eating during your eating windows. As long as you continue to eat enough calories during those eating periods, you should be able to stay away from starvation mode and the weight loss plateau that can come with it. In fact, fasting may boost your metabolic rate and be beneficial to your body in a few ways, including weight loss.

Again, though, it's important to remember that everyone's body and relationship with food is different. Intermittent fasting certainly has weight loss potential, but may not be for everyone, particularly if you have a history of disordered eating, which might be triggered by the fasting structure. It's advised that you talk to a doctor before making any drastic changes to your diet, including intermittent fasting.

If you think you're experiencing a weight loss plateau from starvation mode, there are a few ways to break out of it. Technically, Dr. Lofton told POPSUGAR, you could try to cut even more calories from your diet. That might result in weight loss, but she noted that it's not sustainable. "The problem with lowering your calorie intake further is that that's when the hormonal mechanisms to make you more hungry kick in. It becomes very hard to sustain that lower calorie intake," Dr. Lofton explained.

The other option is to take steps to boost your metabolism. Try eating more protein, drinking lots of water, moving more throughout the day, and increasing your muscle mass by doing resistance training, Dr. Lofton said. (Here are even more ways to increase your metabolism.) Not only are those options more sustainable than continuing to cut calories, they're also healthier and will help you feel better overall than you would with extreme dieting.

Dr. Lofton noted that you and your doctor should also look into other factors that might be causing a weight loss plateau. Some medications, for example, might hinder you from losing weight. Hormones and hormonal changes, like perimenopause, could be at play as well.

A good weight loss practice, in terms of starvation mode and just in general, is to choose long-term lifestyle changes over extreme, restrictive measures. Dieting, Casper explained, tends to be all or nothing: slashing calories, sugar, or carbs. If that leads to major and prolonged caloric restriction, as can sometimes happen, your metabolism can slow down and make weight loss difficult, even if you don't technically enter starvation mode. Not to mention that restricting your food can lead to other unhealthy habits, like overeating when your hunger gets intense enough. "To lose weight and stay healthy for a lifetime," Casper said, "it's important to build healthy habits that work for you and are sustainable, instead of focusing on a short-term restrictive diet."