Do Calorie-Restriction Diets Really Help In Weight Loss?

It’s a common perception that if you eat fewer calories, you can lose weight easily. Although that sounds logically correct, the human body works very differently. It’s an intelligent system that is hardwired to safeguard the body in the absence or the lack of food. So, does a calorie-restriction diet really work?

By eating less than 1,200 calories per day, you’ll soon create a huge caloric deficit, where you’ll tend to burn more calories than you consume. Not only will it result in nutritional deficiencies, but also adversely affect your overall health. Read why many calorie-restriction diets are ineffective and how it can have a negative impact on your health.

What Is A Calorie-Restriction Diet?

Calorie restriction or caloric restriction (CR), also called as energy restriction, is a form of dietary plan, which aims at reducing the calorie intake without causing malnutrition or depriving the body of essential nutrients.

These dietary plans limit the dietary energy intake to improve health and slow aging by means of reducing cholesterol, fasting glucose, and blood pressure.¹ Since energy intake is minimized in caloric-restriction diet, sufficient quantities of vitamins, minerals, and other vital nutrients must be consumed to ensure that your body is not deprived of the vital nutrients.

How Effective Are Calorie-Restriction Diets?

Restricting the intake of calories by following a specific diet is an effective method to control weight and treat obesity. Studies have shown that caloric restriction is the most effective dietary intervention known to regulate aging and increase the healthy lifespan.

It has been closely linked to an increase in lifespan and delay of age-related diseases. However, some studies have also found that caloric restriction was associated with reduced bone mineral density and exercise was recommended to offset such adverse effects.²

But, when it comes to treating obesity, research also shows that dietary fat intake may be more strongly associated than total energy intake to the development and maintenance of obesity.³

Why Don’t Most Calorie-Restriction Diets Work?

Despite the multiple benefits that calorie-restriction diets provide, they may not be always successful. According to recent research, as a survival strategy, human brains can prevent the burning of calories when following a calorie-restriction diet. A recent study conducted on lab mice noted that certain brain cells often prevent the burning of calories when the body does not receive sufficient food.

The researchers tested the role of a specific group (AGRP) of neurons in the hypothalamus part of the brain in lab mice. They found that when these neurons were activated, they make us hungry and urge us to eat. But, when food is not available, they try to conserve energy by switching our body to saving mode and limit the number of calories that we burn.⁴

Although this brain mechanism may have evolved to enable humans to deal with situations like famine, these days, many people create similar circumstances deliberately when they follow a diet that helps them lose weight.

So, for such people, dieting may provide counterproductive results even over prolonged durations as their bodies compensate for the insufficient calories. In short, that’s a lot of sacrifice in exchange for minimal results.

Are There Any Negative Effects?

Absolutely. Depriving your body of the nutrients it requires can certainly have negative health consequences. Here are some ways a calorie-restriction diet can affect you.

1. Reduces Your Immunity

Some people may experience a drop in their immunity levels while following a diet with calorie restriction, especially when it is practiced along with strenuous physical exercises.

Many studies have shown that some people may be more easily affected by the viruses that cause the common cold. The possibility of a reduction in immunity levels is even higher when calorie restriction is combined with a high-level of physical activity.⁵

2. Causes Fatigue And Nutrient Deficiencies

Extreme restriction of calories for a prolonged duration can often lead to fatigue and other nutritional deficiencies. Recent studies reveal that some people may experience tiredness and fatigue when they’re following a calorie-restricted diet with low amounts of carbohydrates.⁶ When you regularly eat fewer calories than your body actually requires, it can cause fatigue and make it more difficult for your body to meet your daily nutrient needs.

In many cases, calorie-restricted diets may not offer ample quantities of iron, folate or vitamin B12, which is known to lead to anemia and extreme fatigue. Besides these nutrients, a calorie-restricted diet may also deprive your body of protein, calcium, B vitamins (biotin and thiamine), vitamin A, and magnesium.

3. Weakens Your Bones

Often, restriction-calorie diets can cause an imbalance in the hormone levels and reduce estrogen and testosterone levels, which may cause weak bones and result in an increased risk of fractures.

Low levels of estrogen and testosterone hormones are considered to affect bone formation and increase bone breakdown, resulting in weaker bones.^{7 8} To further complicate matters, when physical exercise is clubbed with calorie restriction, it can increase the levels of the stress hormone, which again may lead to bone loss.⁹

4. Affects Your Metabolism

Eating fewer calories than what your body needs on a regular basis is known to negatively affect your metabolism causing it to slow down. Research has shown that low-calorie diets can decrease the number of calories your body burns by as much as 23 percent.^{10 11}

Moreover, this low rate of metabolism can continue even long after you stop the calorie-restricted diet.¹² Hence, if you don’t want your weight loss diet to negatively impact your metabolism, it is crucial that you ensure you don’t eat fewer calories than are required to sustain your BMR (basal metabolic rate).

The Verdict

Conclusions from the study conducted on lab mice can help experts to design new or better techniques in the future to help reduce overeating and the risk of obesity. So, an ideal approach for those who want to lose weight is to moderately reduce their calorie intake and simultaneously practice exercises that help in weight loss.