The 500-calorie diet provides around one-quarter of a person’s daily calorie needs. It can help people lose weight but comes with risks. It is only safe to use under a doctor’s supervision.
People on the 500-calorie diet aim to eat only 500 calories a day, which is about a quarter of the daily recommended intake for adults. The upper limit on this diet is 800 calories per day.
In this article, learn the potential uses and risks of a 500-calorie diet.
Help is available
Eating disorders can severely affect the quality of life of people living with these conditions and those close to them. Early intervention and treatment greatly improve the likelihood of recovery.
Anyone who suspects they or a loved one may have an eating disorder can contact the National Alliance for Eating Disorders, which offers a daytime helpline staffed by licensed therapists and an online search tool for treatment options.
For general mental health support at any time, people can call the Substance Abuse and Mental Health Services Administration 24 hours a day at 1-800-662-4357 (or 1-800-487-4889 for TTY).
Many other resources are also available, including:
- The National Association of Anorexia Nervosa and Associated Disorders
- F.E.A.S.T., which provides support and educational resources to friends and family who want to help someone living with an eating disorder
Diets such as the 500-calorie diet are called very-low-calorie diets (VLCD). Although doctors have prescribed VLCDs for many years to treat some conditions, eating so little comes with risks.
Doctors may recommend the 500-calorie diet to help people with obesity or people who are at risk of type 2 diabetes.
VLCDs may also be useful before bariatric and laparoscopic surgery. Losing fat can reduce operative time, blood loss, and the risk of complications.
However, while eating 500 calories per day may help a person lose weight, it is not a suitable or safe diet for everyone and comes with certain health risks.
People should consider the following risks before following a 500-calorie diet without a doctor’s supervision:
1. Chance of nutritional deficiencies
Eating too few calories a day may put people at risk of nutritional deficiencies. For some people, this may lead to malnutrition and a weak immune system.
Certain groups of people may be at higher risk. Older adults, in particular, may be at risk as they are more likely to have reduced nutrient absorption from the small intestine.
2. Possibility of gallstones
People on a 500-calorie diet may lose weight very quickly, which can
Gallstones form in the gallbladder. They can block the bile duct and cause abdominal pain. The following factors can also increase a person’s risk of gallstones:
- fasting for extended periods
- obesity
- pre-existing gallstones
- repeatedly losing and gaining weight
A gradual weight loss plan involving a balanced diet with plenty of fresh vegetables and fruits may help to prevent gallstones.
3. Lack of healthful fats
Of the three macronutrients fat, protein, and carbohydrates, fat is the highest in calories.
Because fats contain more calories, it is difficult to eat enough of them on a 500-calorie diet. Unsaturated fats, such as those in salmon and avocado,
A low fat diet also increases the risk of deficiencies of fat-soluble vitamins, such as vitamin E, and poor absorption of antioxidants.
4. Meal replacements are not a long-term solution
People sometimes use meal replacements for one or two of their daily meals while on a low calorie diet. A meal replacement is usually a liquid alternative, such as a shake or juice, that someone consumes instead of a solid meal.
Although these can be useful, consuming them for a prolonged period can harm a person’s health.
Vitamins, minerals, macronutrients, and phytochemicals from whole foods all have important interactions in the body. Artificial meals cannot replace these vital interactions.
5. It can be costly
Even though someone on the 500-calorie diet is eating less, the cost per pound of food can be higher than on other diets.
The cost of meal replacement foods, such as SlimFast, can be much more than the equivalent amount of whole foods.
6. Lifestyle changes vs. a quick fix
People aiming to lose weight from a VLCD may not implement other weight-loss strategies, such as nutrition counseling and physical activity.
Being on a VLCD does not establish good health behaviors, as the diet is not sustainable over time and people may find it challenging to stick to long-term.
People may see longer-lasting weight changes if they aim for slower, consistent weight loss that involves a balanced diet and regular exercise.
7. Muscle loss
A 2023 review suggests that loss of muscle mass is the main risk of a VLCD. To minimize this risk, the researchers suggest that people should:
- eat enough protein
- work with a healthcare professional
- maintain muscle with a resistance exercise training plan
8. Missing out on social events
Eating out can be difficult on a 500-calorie diet. Some restaurants do not reveal the total calorie count of their meals, and meals in restaurants may have higher calorie counts than those a person makes at home.
Being on the 500-calorie diet may also cause anxiety about ordering food or eating with family and friends.
9. Unsuitable for people with certain health conditions
According to a 2018 article, people with the following health conditions should not try a VLCD:
- arrhythmia
- psychiatric disorders
- acute heart failure
- type 1 diabetes
- liver failure
- kidney failure
People should consult a doctor before starting a 500-calorie diet to ensure it is a safe option for them.
10. Possible decrease in bone health
The long-term effects of a VLCD on bone health are unknown because people do not typically use the diet for prolonged periods.
However, a lack of essential minerals and nutrients may weaken bones over time.
Other low calorie diets include the following:
- The 5:2 diet: On the 5:2 diet, people eat a regular amount of healthful calories for five days of the week, then limit their calorie intake to 500 to 600 calories for two non-consecutive days.
- Time-restricted feeding: Time-restricted feeding extends the nighttime fast to between 12 and 16 hours. People can only eat during certain hours of the day. For example, they may fast during the night and only eat between 9 a.m. and 7 p.m.
- Alternate-day fasting: During alternate-day fasting, people alternate their daily calorie intake, eating 500 calories one day and consuming a regular number of healthful calories the next.
Because these diets do not involve consistently low levels of calories, people can eat higher quantities of vegetables, fruit, whole grains, and healthful fats. These diets may also be easier to follow and stick with.
People can also consider slower weight changes by exercising regularly, eating a balanced diet, and managing portion sizes. Slow, consistent weight loss may be easier to maintain long-term than fast weight loss from a VLCD.
A limited variety of foods and the risk of nutritional deficiencies can make a 500-calorie diet dangerous.
It is essential for people to get supervision from a doctor and a dietitian before embarking on this diet. Anyone considering this diet should speak with a healthcare professional first to ensure it is safe for them.
If someone is on a 500-calorie diet and notices a decline in their health or new symptoms, they should contact a doctor.
A 500-calorie diet may be beneficial in the very short term for some people with obesity or as a pre-operative measure.
However, people just looking to lose weight should try making sustainable diet and lifestyle changes, such as increasing their vegetable intake in all meals.
They may also consider alternative diets, such as the 5:2 diet, time-restricted feeding, or alternate day faster. People should not use the 500-calorie diet for longer than a doctor recommends.