A 500-calorie diet is an extreme form of a very low-calorie diet (VLCD). VLCDs are meant for people who are very overweight and have been unable to lose weight after trying many diet plans. This diet can be dangerous and requires medical supervision. It involves severely restricting daily calorie intake, often relying on liquid supplements, meal replacement products, or snack bars. While it can lead to rapid weight loss, it also carries significant health risks.
Understanding the 500-Calorie Diet
The 500-calorie diet is an extremely strong and strict plan. It limits your daily calorie intake to an exceptionally low level, often replacing normal eating habits with liquid supplements, meal replacement products, or snack bars for a specific period. With fewer calories, the body burns stored fat for energy, leading to fast weight loss.
This diet is sometimes known as the 5:2 intermittent fasting plan, where calorie intake is restricted to 500 calories on two non-consecutive days each week while maintaining normal calorie consumption on the other five days. On fasting days, calorie intake typically covers only 20-25% of energy needs.
Studies suggest that intermittent fasting may help overweight and obese individuals lose weight. However, findings remain inconclusive, and more research is needed to confirm these claims. While the 500-calorie diet can aid in rapid weight loss, it is not suitable for everyone.
Potential Benefits of a 500-Calorie Diet
The benefit of the 500-calorie diet lies in its ability to promote rapid weight loss. Following this diet can enhance metabolism, accelerate fat oxidation, and support effective weight loss. This diet is often recommended for individuals who need to lose weight quickly to prevent potential health risks associated with excess weight. VLCDs may also be useful before bariatric and laparoscopic surgery. Losing fat can reduce operative time, blood loss, and the risk of complications.
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Risks and Dangers of a 500-Calorie Diet
However, the 500-calorie diet is not suitable for everyone, as long-term adherence can lead to severe nutritional deficiencies. A study published in the Journal of Nutrition found that extremely low-calorie diets, such as the 500-calorie diet, can cause significant micronutrient deficiencies. The study revealed a significant decrease in levels of vitamin D, vitamin C, and zinc in obese individuals following the 500-calorie diet for more than 12 weeks. Additionally, this diet may lead to side effects such as nausea, fatigue, diarrhea, increased sensitivity to temperature, menstrual irregularities, and hair loss. The lack of dietary fiber can also result in constipation. Furthermore, the immune system may be weakened, making the body more susceptible to various illnesses.
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.
The greatest dangers associated with a 500-calorie diet relate to vitamin and mineral deficiencies. Vitamin and mineral deficiencies can lead to many health problems. In fact, most people cannot meet their vitamin and mineral requirements if they eat less than 1200 calories per day. For example, if your diet lacks the mineral zinc, which is in pumpkin seeds and beef, you can suffer hair loss. Low iron intake can lead to anemia, while chronic low intake of calcium and vitamin D can lead to osteoporosis later in life. If you don’t get enough of the vitamin niacin, found in tuna and dates, you could be at risk for heart attack due to clogged arteries. Always consider the full nutritional makeup of the foods you eat, not just their calories.
Gallstones
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.
Read also: Dangers of the 800 Calorie Diet
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, offer certain health benefits to the body when someone eats them in moderation. A low fat diet also increases the risk of deficiencies of fat-soluble vitamins, such as vitamin E, and poor absorption of antioxidants.
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.
Cost
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 can be much more than the equivalent amount of whole foods.
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.
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:
Read also: Diet Before Bariatric Surgery
- eat enough protein
- work with a healthcare professional
- maintain muscle with a resistance exercise training plan
A 500-calorie diet can also put you at danger for muscle loss. Sharon Palmer, R.D., dietitian and author of “Plant-Powered for Life,” points out, “Once your body has consumed your fat reserves, it begins to burn healthy muscle.” At first, muscle loss may seem like you are losing more weight, but keep in mind that not all weight is bad. To keep your body healthy, you need to be able to build muscles. A healthy diet burns fat, not muscle.
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.
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.
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.
Metabolic Changes
Another health risk to keep in mind when considering a 500-calorie diet is that your metabolism will change when you reduce the amount of calories you eat for a long enough period of time. Severe calorie restriction for prolonged periods of time will lead to a slower metabolism. This can lead you to burn fewer calories. Also, when you lose weight, you then need fewer calories to maintain your new weight than you needed for your original weight.
Dr. Mindy Haar, Ph.D., R.D., C.D.N., of the New York Institute of Technology School of Health Professions, says, “Many people think that they can stick with a diet for the short term, lose the weight, and then go back to eating the way they were before. But if they do so, they will regain weight until they reach their original weight.”
Resting energy expenditure (REE), weight, and body composition were measured up to seven times in 13 obese women during a 24-wk study. Patients were randomly assigned to a very-low-calorie diet (VLCD, 500 kcal/d) or a balanced-deficit diet (BDD, 1200 kcal/d). After 8 wk of supplemented fasting, REE of the VLCD patients decreased by 17% whereas that of the BDD patients was virtually unchanged. REE of the VLCD patients increased during 12 subsequent weeks of realimentation such that differences in REE between the two groups were not statistically significant at week 24 (VLCD = -11%, BDD = -2%). Reductions in weight and fat-free mass (FFM) were 12.1% and 3.6% for the VLCD patients and 10.6% and 4.1% for the BDD patients, respectively. There were no significant differences between the groups in pre- to posttreatment changes in REE normalized to FFM. Results suggest that REE recovers partially after consumption of a VLCD.
Important Considerations
Medical Supervision
You should only conduct a 500-calorie diet under a doctor’s close supervision. Though you may lose weight, you are at risk of malnutrition, which can cause many health problems. A doctor will prescribe a 500-calorie diet if he or she has decided that it’s critical for you to lose weight. They do this by weighing your general health concerns against the risks and potential complications of drastic calorie reduction. If your doctor hasn’t recommended a 500-calorie diet, you should not try this diet. A diet like this has risks and precautions associated with it. A doctor should supervise you while on this diet.
The 5:2 Diet Plan
Some people use a 500-calorie diet as part of the recently popularized 5:2 intermittent diet plan. Under this plan, you eat a balanced Mediterranean-style diet of about 2000 calories for five days of the week and then limit yourself to 500 low-carbohydrate calories per day for the other two days. The two “fasting” days are usually nonconsecutive. There is very little evidence to support the benefits of 5:2 intermittent dieting over daily calorie reduction.
Understanding 500 Calories
You can get an idea of how much (or how little) 500 calories is when you consider the calorie count of popular foods. The USDA calculates that one ounce of dry-roasted peanuts (about 28 peanuts) contain about 166 calories, while a slice of pepperoni pizza contains about 261 calories. A medium-sized apple contains about 77 calories, while two pieces of fried chicken breast contain about 324 calories. You might also want to consider how many calories you burn in a day. According to the Harvard Medical School, a 185-pound person burns 94 calories by just sitting in a one-hour meeting.
Nutritional Balance
One of the problems with a 500-calorie diet is that it places no limits on the fats and carbohydrates you consume. A serving of chocolate pound cake and a glass of milk adds up to about 500 calories. However, that so-called meal doesn’t even come close to giving you the nutrients you need, even if you’re just sitting in a meeting. Regardless of calorie count, a well-rounded diet includes fruits and vegetables, lean proteins, and whole grains. Being healthy is about a lot more than just a number.
Alternative Diets
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. 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.
Recipes for Fasting Days (Sample)
Here are a few breakfast, lunch, and dinner recipes to consider for a variety of eating patterns:
Low-Calorie Vegan Recipes
- Breakfast: Scramble ¼ block of firm tofu with ½ cup of chopped green peppers. Serve with ½ cup of raspberries on the side.
- Lunch: Mix ½ cup of canned chickpeas with ¼ of an avocado. Wrap the mixture in 2 romaine lettuce leaves.
- Dinner: Mix together ½ cup of quinoa (cooked in water), ½ cup of chopped broccoli, and ½ cup of chopped red peppers.
Low-Calorie Vegetarian Recipes
- Breakfast: Scramble 2 egg whites with 1 slice of nonfat Swiss cheese, and serve with 1 cup of raspberries on the side.
- Lunch: Eat 2 tablespoons of peanut butter on 1 slice of whole-wheat toast.
- Dinner: Bake ¼ block of firm tofu with herbs and spices, and serve with 1 ½ cups steamed broccoli.
Low-Calorie and Low-Carb Recipes
- Breakfast: Scramble 3 egg whites with 1 slice of nonfat Swiss cheese and ½ cup of chopped green peppers.
- Lunch: Mix 3 ounces (oz) of lean grilled chicken breast with ¼ of an avocado and wrap in 2 romaine lettuce leaves.
- Dinner: Bake 3 oz of salmon and serve with 1 cup of steamed cauliflower.
Low-Calorie Recipes for Omnivores
- Breakfast: Scramble 4 egg whites and serve with 1 slice of whole-wheat toast.
- Lunch: Mix 3 oz of canned white tuna (water-packed) with ¼ of an avocado.