Diet alone is not enough to achieve and maintain a healthy weight. It is much more effective to combine diet with exercise and changing your eating habits.

The diet is especially effective for initial weight loss. Body weight is determined by the balance between calorie intake and expenditure. The main expenditure of calories in the average person  is spent on maintaining body functions at rest and basal metabolism (usually about 60-70% of total calorie expenditure), digestion and assimilation of food (about 5-10% of calories consumed) and physical activity (25 –35% of calories).

The calorie requirement of a person depends on body weight and activity.

The Basic Calorie Requirement (BMR) is calculated using the   Harris-Benedict formula . For men, this formula looks like this: BMR = 88.36 + (13.4 x weight, kg) + (4.8 x height, cm) – (5.7 x age, years). Harris-Benedict formula for women: BMR = 447.6 + (9.2 x weight, kg) + (3.1 x height, cm) – (4.3 x age, years).

To determine the body’s total calorie requirements, multiply the BMR value obtained, corresponding to gender, age and weight, by the daily activity coefficient, which is determined depending on the level of physical activity during the week.

There are five types of physical activity – minimum level (no physical activity) – coefficient 1.2, low level (physical activity 1-3 times a week) coefficient 1.375, medium level (physical activity 3-5 days a week) – coefficient 1, 55, high level (physical activity 6-7 times a week) – coefficient 1.725 and very high level (training more often than once a day) – coefficient 1.9.

To lose 450 grams of weight, a person must consume 3500 fewer calories than they spent. For example, to lose 450 grams each week, you need to maintain a negative energy balance of 500 calories per day. Obesity occurs as a result of a long period of positive balance, when the consumption of calories exceeds their expenditure.

To reduce body weight, it is necessary to create a negative energy balance. This can be done by decreasing your calorie intake and / or increasing your physical activity. Any of the following can burn approximately 500 calories: jogging for 45 minutes, playing tennis for 60 minutes, walking for 75 minutes, cycling for 90 minutes. It is important to understand that weight loss means less body fat, not muscle mass.

Since glucose can be formed from amino acids and fat, carbohydrates are not considered essential in the diet.  However, a healthy diet requires a minimum of 100 grams of carbohydrates per day to prevent ketosis and excessive loss of electrolytes and water in the urine. To maintain muscle mass, the body requires a minimum of 0.8 g of protein per 1 kg of body weight.

As the amount of food consumed decreases with diets aimed at weight loss, the intake of other essential nutrients decreases accordingly. That is why it is advisable, after consulting a doctor, to take multivitamin-mineral complexes in order to prevent a lack of vitamins and minerals.
There are  hundreds of diets nowadays that promise effective weight loss. Such diets can be  balanced, low in carbohydrates, high in carbohydrates, high in protein, and high in fat.

In addition, advertisements for “miracle pills” continue to appear, claiming that such pills will help people lose weight easily and without any restrictions.

It should be remembered that diets with unusual food combinations, such as low-carb, high-protein, and other radical diets, carry significant risks to your health and do not provide any weight loss benefits.

The best way to lose weight is to eat a balanced, moderately hypocaloric diet. In order to choose the right diet for you, you need to contact a specialist.

Any diet of less than 1000 calories per day should only be used on the advice and supervision of a physician.

Once excess weight is lost, it should be maintained. A number of animal studies suggest that repeated cycles of weight loss and recovery   increase a certain amount of weight loss and reduce weight recovery with repeated cycles. This is due, at least in part, to adaptations of the basal metabolism as a result of diet.

In the most severe cases of obesity (with morbid obesity), surgical treatment can be used.