People with overweight or obesity may use a low calorie diet to lose weight. A doctor may recommend this for healthy weight loss. However, there some potential risks.
This article will define low calorie diets, outline how many calories are in different foods, and discuss diets that involve intermittent fasting.
It will also include tips for weight loss and low calorie meal suggestions.
The following table details estimated calorie needs per day by age, sex, and physical activity levels, according to Dietary Guidelines for Americans 2015–2020.
Although this provides a guideline, caloric intake varies from person to person, and other factors — such as height, weight, and weight goals — can affect how many calories a person should consume.
According to experts, to lose weight safely and successfully, people should:
- Aim to lose 1–2 pounds of weight per week for a period of 6 months.
- Do this by reducing their calories by 500–1,000 per day.
- Include 30 minutes of moderate intensity physical activity on most days.
- After 6 months, assess their weight loss and consider their next steps.
When choosing a low calorie diet to lose weight, a person must make sure that their meals are nutritionally balanced.
There are various meal plans available online. A person should preferably choose a diet that a nutrition professional has designed to ensure that the meals contain vital nutrients, such as vitamins, minerals, and fiber.
Choosing healthful, unprocessed foods to make up the required number of calories is the best option to ensure adequate nutrition. For example, a large burger meal with fries and soda contains 1,320 calories, but this would not be sufficient to meet a person’s key nutrient needs per day.
A very low calorie diet consists of fewer than 800 calories per day. Some very low calorie diets consist of 500 calories per day. A person should not start a very low calorie diet without medical support, as it could be dangerous to their health.
The doctor may give a liquid form of a very low calorie diet for a specified amount of time. The drink will contain vitamins, minerals, electrolytes, and fatty acids. They may also monitor weight loss and blood pressure and take blood tests to ensure that the person stays within healthy parameters.
Intermittent fasting is a dietary approach that involves periods of either no food or very low calories and periods of unrestricted eating. There are several different ways to achieve this:
- Alternate day fasting: For this approach, a person alternates between days of normal eating and days of reducing calories by 25% or more of their daily needs.
- Whole day fasting: This approach involves fasting on certain days of the week. For example, the 5:2 diet allows no food restriction on 5 days of the week and 400–500 fewer calories on the other 2 days of the week.
- Time restricted feeding: For this approach, a person only eats within a specific time frame — for example, between 8 a.m. and 3 p.m. — and fasts for the remaining hours of the day. There are various versions of this, such as the 16:8 diet.
Research into intermittent fasting is controversial, with some sources suggesting that physiological adaptations to calorie restriction may prevent further weight loss.
The number of calories in different foods depends on what macronutrients they contain.
According to the United States Department of Agriculture:
- carbohydrates provide 4 calories per gram
- protein provides 4 calories per gram
- fat provides 9 calories per gram
People can find out how many calories are in different foods by using an online calculator or app. Apps often allow people to input meals they regularly eat to calculate how many calories they consume per day.
The following is a 1,200-calorie 1-day meal plan from the National Heart, Lung, and Blood Institute. The meal plan accounts for a grand total of 1,247 calories. It is based on traditional American cuisine.
It is important to note that the following meal plan is only a suggestion. It does not take any dietary restrictions into account or meet the daily recommended allowance for all nutrients.
- 1 medium slice of wholewheat bread with 2 teaspoons (tsp) of regular jelly
- 1/2 cup of shredded wheat with a cup of 1% fat milk
- 3/4 cup of orange juice
- 1 cup of regular coffee
- a roast beef sandwich made with 2 medium slices of wholewheat bread, 2 ounces (oz) of lean, unseasoned, roast beef, 1 lettuce leaf, 3 slices of tomato, and 1 tsp of low calorie mayonnaise
- 1 medium apple
- 1 cup of water
- 2 oz of salmon cooked in 1.5 tsp vegetable oil
- 3/4 of a medium baked potato, topped with 1 tsp of margarine
- 1/2 cup of green beans
- 1/2 cup of carrots
- 1 small white dinner roll
- 1 cup of unsweetened iced tea
- 2 cups of water
- 2.5 cups of popcorn prepared with 3/4 tsp of margarine
Low calorie diets can help people lose weight, but evidence as to their long-term effectiveness is controversial.
People should only use a very low calorie diet if a doctor has recommended this, as the doctor needs to ensure that someone stays healthy while losing weight.
People can use an online meal planner or app to plan their weekly meals and monitor how many calories they consume each day.
In addition to following a healthful diet, people should also incorporate an exercise routine into their day for effective weight loss.