Too few calories can hamper your metabolism, sabotaging any goal to lose weight. Although some combinations of macronutrients or types of foods may affect weight loss synergistically, when it comes to dropping pounds, there's no denying that calories matter.
But what some people may not realize is there's such a thing as eating too little for weight loss. It's true, says Lisa Young, Ph. D., R.D., a nutritionist and adjunct professor of nutrition at New York University—cutting too many calories can actually slow down the weight loss process.
The simple answer is no. There is no research to support the concept that not eating enough (or severe calorie restriction) can cause you to gain weight. Time and time again research has shown us that when we eat fewer calories than what we burn, we lose weight.
You Might Be Eating Too Little
This phenomenon is called “starvation mode,” and while your body isn't actually starving, it will naturally hold onto whatever calories it receives in an effort to help you maintain your energy balance.
When you eat less than you need for basic biological function (about 1,200 calories for most women), your body throws the brakes on your metabolism. It also begins to break down precious, calorie-burning muscle tissue for energy, says Benardot.
Some health conditions may be the reason why you are in a calorie deficit and not losing any weight. These mainly include hormonal imbalances such as hypothyroidism, illnesses that affect insulin response and glucose metabolism, such as diabetes, or a mix of the two.
Some research also suggests that weight loss is about more than the calories a person consumes and burns. The body may change the rate at which it burns calories depending on how many calories a person eats. Therefore a person on a 1,200 calorie diet may burn fewer of them. This can slow weight loss.
However, sometimes water retention can be caused by other aspects that can be the reason behind calorie deficit but not losing weight. Salty food, high carbohydrate intake, lack of exercise and some medications can cause water weight gain even on a caloric deficit (10).
However, other studies show that while consuming 1,000 calories a day may result in significant weight loss, most people cannot sustain it and often experience significant weight regain . The reasons include regaining lost muscle mass and increased appetite. Also worth noting is that the human body can adapt.
The diet doesn't have enough calories
Eating too little — say, 1,000 calories a day — can prevent you from losing weight, too. "When you don't eat enough, your body is starving and it's not going to lose any extra weight" because it needs those energy stores to keep you alive, Fakhoury said.
You will lose up to 10 pounds (4.5 kgs) if you consume 800 calories and exercise regularly. Make sure your doctor or nutritionist is aware of your diet pattern.
1,700-1,800 calories could be a good weight loss target for some, but as a very active person with decent muscle mass, that may be too low for you to stick to. "Being in a smaller deficit will make it a lot easier to stick with and will help you retain more muscle," Wilson said.
So as you lose weight, your metabolism declines, causing you to burn fewer calories than you did at your heavier weight. Your slower metabolism will slow your weight loss, even if you eat the same number of calories that helped you lose weight. When the calories you burn equal the calories you eat, you reach a plateau.
According to the Harvard Medical School, the least number of calories that one can consume a day while trying to lose weight is 1,200 a day for women and 1,500 a day for men (5). In light of this, the 800 calorie diet is not a safe eating plan for anyone unless they are under medical supervision.
You're eating less, but could make healthier choices
This is where a calorie deficit alone isn't a magic formula. Reducing your calories to 1,500 a day but eating processed foods instead of healthy fats, protein and fruit and veg won't give you long-term results. You could also be limiting how healthy you feel overall.
A plateau can last between eight to twelve weeks, but it also varies individually. After this, it's much easier for us to recommence a period of weight loss. Sustainable weight loss isn't a sprint.
Most people who have difficulty losing weight are simply eating too many calories. An important factor in weight loss is how many calories you're eating versus how many calories you're burning. It may seem easy, but if you're not tracking your calories each day, you may be consuming more than you think.
The 1200-calorie diet is geared toward women. Men's bodies require a higher caloric intake. This means that a typical woman can eat between 1200 and 1500 calories a day to lose weight. A typical male body needs about 1500 to 1800 calories daily to lose weight.
However, calorie intake should not fall below 1,200 a day in women or 1,500 a day in men, except under the supervision of a health professional. Eating too few calories can endanger your health by depriving you of needed nutrients.
No matter what type of diet you follow, to lose weight you need to burn more calories than you take in each day. For most people with overweight, cutting about 500 calories a day is a good place to start. If you can eat 500 fewer calories every day, you should lose about a pound (450 g) a week.
From constipation to immune dysfunction, not eating enough can lead to a host of health issues. One of the main reasons that undereating can lead to weight gain is because consuming too few calories can cause your resting metabolic rate to slow down. This means you may burn fewer calories throughout the day.