Many diets encourage you to reduce your food intake and eat fewer calories to reach your weight loss goals. However, drastically restricting calories can come with potential side effects or even make your body go into starvation mode.
Starvation mode can reduce energy expenditure, make it difficult to lose body fat, and possibly lead to weight gain.
In this article, you’ll learn about the myths and facts behind long-term caloric restriction, if starvation mode is as damaging as some claim, and what to look out for when it comes to keeping your metabolism healthy.
You’ll also learn the difference between long-term calorie restriction and intermittent fasting, as well as how to avoid a weight loss plateau.
Starvation mode is one name for your body’s natural response to a severe calorie deficit.
Because your brain and body are more interested in long-term survival than losing body fat, eating too few calories can act as a starvation signal. As a result, your body may put the brakes on fat loss[*].
The scientific name for starvation mode is “adaptive thermogenesis,” also known as metabolic adaptation. During adaptive thermogenesis, your cells, central nervous system, and hormones work together to reduce your metabolism and stabilize your body weight[*][*][*][*].
Staying in adaptive thermogenesis long-term can result in serious hormonal imbalances, extreme difficulty in maintaining a stable body weight, and other health problems. Some people refer to these harmful effects as metabolic damage[*][*].
Metabolic damage can lead to disruptions in hunger hormones, lean muscle loss, and — in severe cases — organ damage. Researchers have documented the occurrence of hair loss, diabetes, and heart failure due to metabolic damage from long-term, low-calorie diets[*][*][*].
Is Starvation Mode Real?
While starvation mode is a real thing, people often use the term loosely. As a result, you may have encountered some misconceptions about it.
Here are some myths you may have come across:
- You can go into starvation mode by missing a meal or trying intermittent fasting[*].
- You need to eat lots of tiny meals each day to prevent adaptive thermogenesis.
- If you aren’t losing weight, it’s because you’re in starvation mode. (Difficulty in losing weight doesn’t necessarily mean you’re in starvation mode. Weight loss can be challenging all by itself, and you may be making other common keto diet mistakes.)
There isn’t a precise formula that can tell you whether a diet will put you into starvation mode or not, but you can look out for warning signs.
Starvation can occur when you start restricting the number of calories you eat in a very extreme way. To avoid developing side effects, pay attention to the signs your body sends you.
#1: You’re Constantly Hungry
When you start a low-calorie diet, being hungry all the time is quite common. If you’re in the process of losing body fat, it’s normal to feel hunger when you wake up, between meals, before bedtime, or while you’re fasting.
If you just started your keto journey, you may not be fat-adapted yet, which can result in short-term cravings.
However, if you feel hungry constantly, or you’re still hungry after finishing meals, you may be close to starvation mode. Severe undereating and constant hunger are counterproductive because they make it difficult to stick to your diet.
Over time, excessive hunger can lead to binge eating or unconscious overeating, which can derail your efforts and lead to unwanted weight gain.
#2: You’re Losing Muscle Mass
If your goal is to lose weight, there’s an enormous difference between burning fat and losing lean muscle mass. When you pursue weight loss at any cost, the likely result is that you’ll lose lean muscle mass instead of burning fat[*].
Losing muscle mass can hinder fat loss and doesn’t enhance your appearance, improve your health, or reduce your risk of disease. The more you restrict your calories long-term, the more lean body mass you’ll lose, and the more your metabolism slows down. It can be a vicious cycle[*][*].
During healthy fat loss, your waist circumference and other areas where you carry excess body fat should decrease in size, making your clothes fit better.
In contrast, losing muscle mass can actually make you look less slender because your shoulders, glutes, arms, and thigh muscles might lose their shape and tone.
Depending on your body type, it isn’t always easy to tell whether you’re losing muscle mass, but taking progress photos can help. To be on the safe side, you can have your body composition measured using a DEXA scan or the caliper method two or three times per year.
#3: You Feel Tired and Irritable
Long periods of severe calorie restriction can lead to fatigue and irritability. Everyone has bad days, but if you’ve had a bad week, month, or year, your diet could be at the root of your problems.
When you undereat, your body responds to the threat of starvation by adjusting thyroid hormones, cortisol, and neurotransmitters like dopamine and adrenaline. Their function is to help you conserve energy and encourage you to look for food[*][*][*].
As a result, you’re more likely to feel tired and grouchy.
#4: Your Exercise Performance Is Suffering
When you eat too few calories, your body has a hard time repairing itself, and your exercise performance might be affected. If you’re getting less physically fit as you lose weight, consider it a warning sign that you aren’t eating enough.
Increasing your strength levels and aerobic fitness requires sufficient calorie intake to fuel your performance and recover from exercise.
Undereating can deprive your muscles and organs of much-needed nutrients and even create hormone imbalances, leading to poor performance[*].
If you’re excessively sore, falling behind on exercise performance, or experiencing signs of overtraining, it’s time to take a closer look at your diet.
Starvation can happen for those who follow extremely strict low-calorie diets. However, there are ways to lose weight, have more energy, and consume the nutrients you need without starving.
Here are some of the reasons a keto diet might be right for your weight management goals.
#1: Stay in Fat-Burning Mode
While eating fewer calories is one aspect of losing weight, another way to help your body burn fat is to crank up its fat oxidation capacity. If you’re having trouble losing weight, you may not be fat-adapted[*].
However, by using fat as fuel, you can avoid starvation mode by relying on your body fat stores.
#2: Eat Nutrient-Dense Foods
In addition to too few calories, inadequate vitamin, mineral, and micronutrient intake can also trigger starvation. Your body needs these essential nutrients to function and repair itself. Nutrient deficiencies in your diet can lead to excessive hunger, tissue breakdown, and health problems[*].
That’s why it’s critical to include a diverse range of nutrient-dense foods in your fat loss diet. As opposed to calorie-dense processed foods that are low in nutritional value, there are plenty of nutrient-dense keto-friendly foods to choose from on the ketogenic diet.
#3: Use Ketones and Medium-Chain Triglycerides (MCTs)
Starvation mode usually occurs when your brain senses low energy intake, at which point it signals your body that there’s a major risk of starvation. Since your brain consumes about 20% of your overall energy needs each day, it’s vital to fuel it adequately[*].
#4: Eat Enough Protein
Most keto diets include about 20% protein, which translates to 75 grams of protein per day for a 1,500-calorie diet, or 100 grams for a 2,000-calorie diet.
To determine your unique protein needs, use the keto macronutrient calculator to calculate your macros and ensure you’re meeting your body’s daily needs.
#5: Lift Weights
Strength training can’t rescue you from starvation mode by itself, but it’s an excellent choice to improve weight loss results[*].
It’s also a great way to track your eating habits. If your performance is getting better every week, you’re probably not starving.
Eating enough protein and calories is essential to ensure recovery and prevent overtraining. If you’re undereating, lifting weights could create more problems than it solves.
You Can Avoid Starvation Mode With a Keto Diet
No matter what you choose to call it, starvation mode can occur. But it’s not quite as common as many people think.
If you’re perpetually hungry, losing muscle mass, have less energy than usual, or notice reductions in your physical fitness, it’s time to revamp your eating habits.
By eating nutrient-dense foods, harnessing ketosis, and lifting weights, you’re supporting a healthy fat loss. At the same time, you’re helping your body to build muscle and prevent starvation mode.
To read more about how a keto diet promotes weight loss and other health benefits, check out these articles: