Those who are trying to start losing weight or perhaps want to shed a few pounds before a big event or vacation may be tempted to try crash dieting. While it's true that you need to eat fewer calories than your body consumes daily to lose weight, in reality, crash diets can work against you — and can make losing weight more difficult.
Crash diets have been around for years, but have remained popular lately thanks to influencers and social media. Typically, these diets involve dramatically reducing your calorie intake to 800-1,200 calories per day for a few weeks at a time.
Proponents of these diets claim that they can lead to rapid weight loss, which may explain why they are so popular. In fact, research has shown that these diets can be very effective for some people.
In a study of 278 obese adults, a 12-week intensive diet containing 810 calories per day resulted in greater weight loss after 12 months than people who reduced calories through portion control. The extreme diet group lost an average of almost 11 kg compared to just 3 kg in the moderate diet group.
Likewise, a study showed that low-calorie diets can be beneficial for people with type 2 diabetes. Researchers found that 60% of participants who ate 600 calories daily for eight weeks were able to put their type 2 diabetes into remission. . They also lost an average of about 15 pounds.
A 12-week follow-up showed that participants regained about 3 pounds, but more importantly, their blood sugar levels remained similar.
But while these diets can lead to short-term weight loss success in some people, they can have the long-term consequences of damaging your metabolism.
This may explain why about 80% of diets fail, as a person ends up regaining all the weight they lost or even gaining more weight than they lost.
Crash diets and metabolism
Your metabolism is the sum of all the chemical reactions in your body. It is responsible for converting the food we eat into energy and storing any excess energy in the form of fat. Your metabolism is affected by many things – including diet, exercise and hormones. Crash diets affect all of these components.
With a crash diet, you consume much less food than usual. This means that your body does not need to use as much energy (calories) to digest and absorb the food you eat. You also lose muscle. All of these factors reduce your metabolic rate, which means your body will burn fewer calories when you're not exercising.
In the short term, crash diets can lead to fatigue, making any activity (let alone exercise) difficult. This happens because there is less energy available, and what is available is prioritized for life-sustaining reactions.
In the long term, extreme diets can change the hormonal makeup of our body. They increase our stress hormones like cortisol. Over a long period of time, usually months, high cortisol levels can cause our bodies to store more fat.
Crash diets can also reduce levels of T3, which is produced by the thyroid gland. It's essential for regulating our basal metabolic rate (the number of calories your body needs to maintain itself). Long-term changes in T3 levels can lead to hypothyroidism and weight gain.
All of these changes together make your body more likely to gain weight when you start consuming more calories again. These changes can last for months, if not years.
If you are trying to lose weight, the best strategy you can use is to follow a gradual, long-term weight loss diet.
Crash diets have been shown to be more sustainable and have less negative impact on your metabolism than crash diets. Taper diets can also help maintain adequate energy levels for exercise, which may help you lose weight.
These types of diets also maintain the function of our mitochondria, which are the calorie-burning centers in our muscles. This creates a greater ability to burn calories even after you finish the diet.
The ideal diet is one that reduces body weight by about 0.5 to 1 kilogram per week. The number of calories you need to eat each day depends on your starting weight and how physically active you are.
Eating certain foods can also help maintain your metabolism while dieting.
Fats and carbohydrates use fewer calories to fuel digestion than proteins. In fact, high-protein diets increase metabolic rate by 11-14% above normal levels, while diets high in carbohydrates or fat do so by only 4-8%. As such, try to ensure that about 30% of the calories in your day consist of protein when trying to lose weight.
Protein-rich diets also help you feel full longer. One study found that when a participant's diet consisted of 30% protein, they consumed 441 fewer calories over the 12-week study period compared to a diet containing 15% protein. In the end, this resulted in a weight loss of 5 pounds, including 3.7 pounds of fat loss.
Although it may be tempting to go on a crash diet if you're trying to lose weight quickly, doing so can have long-term consequences on your metabolism. The best way to lose weight is to slightly reduce the number of calories you need daily, exercise, and eat plenty of protein.
Published in Science Alert
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