What Is 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.