Can You Survive on 500 Calories a Day?

Some diets ask you to do the unthinkable, and trying to survive on 500 calories a day is one of them. In an attempt to lose weight as quickly as possible, many people seek out extreme eating plans that promise quick results.

And while you may be able to follow a very low-calorie diet (VLCD) for a short time, this is not the type of plan you should attempt without medical supervision. Before deciding on a particular diet, make sure to do your research and ask a lot of questions. There are a lot of plans that will help you reach your goals without depriving yourself of proper nutrients.

If you have a significant amount of weight to lose, your doctor may prescribe a medically-supervised very low-calorie diet. These programs typically provide fewer than 1000 calories, with the majority of them restricting calories to 800 and below. Most of these plans also require the use of supplements such as meal replacement shakes.

Diets this low in calories rarely provide enough nutrients to keep your body healthy. This can lead to serious, and potentially fatal health problems, according to Michigan Medicine. Some of the more common issues dieters face on these types of plans include constipation, fatigue, nausea, diarrhea, mineral and electrolyte imbalances and gallstones. Plus, if you have blood clotting problems, heart problems, liver disease, kidney disease, bleeding ulcers or have had a stroke, very low-calorie diets are not recommended.

Restricting your calories, and consequently, key nutrients, can slow your metabolism and cause your body to go into survival mode. The Academy of Nutrition and Dietetics says when this happens, your body starts breaking down muscle to release the glucose stored inside to use for energy. Additionally, women who lower their calories too much may experience missed or irregular periods, which may ultimately lead to an increase in bone loss.

Read more: Sample 500-Calorie Diet Plan

Unless you are following a medically-supervised diet, restricting your calories to 500 a day is not recommended. The good news is there are several ways to lose weight and keep it off, by making simple lifestyle modifications.

If you're not sure how to differentiate between a realistic and sustainable weight loss plan and a fad diet, a good rule of thumb is to steer clear of any diets that require you to follow a rigid menu, allows only specific food combinations, eliminates entire food groups or doesn't include exercise as part of the plan.

The Mayo Clinic recommends a weight loss of one to two pounds a week, which you can reasonably accomplish by consuming 500 fewer calories a day and burning 500 calories through exercise. This results in a net loss of 1000 calories, which equals a two-pound weight loss. That said, your starting calorie count should be within the recommended range based on age, physical activity level and sex.

For example, a moderately active, 36-40-year-old woman should eat about 2,000 calories a day to maintain her weight. A man of the same age and activity level can consume 2,600 calories a day. There are several charts and calculators online that will help you figure out your caloric needs.

Read more: Minimum Amount of Calories Needed Per Day to Survive

Cutting your calorie level to extremely low levels can equal disaster when it comes to exercise and being physically active. Not only is it difficult to carry out common daily tasks such as working, caring for children and routine housework, but it's also nearly impossible to add exercise to your day if you are trying to survive on 500 calories.

According to the Center for Disease Control and Prevention, a 154-pound person can expect to burn about 230 calories walking for 30-minutes at a moderate pace. That same person can burn 165 calories in 30-minutes doing light gardening or yard work. Just those two very light activities combined puts you close to the number of calories you're eating.

And while exercise alone may not result in a significant reduction in your weight, especially if you are not making changes to your diet, being physically active does help to keep the weight off. A March 2019 study from the University of Colorado Anschutz Health and Wellness Center, published in Obesity, looked at successful weight-loss maintainers and found that those who engage in high levels of physical activity prevented weight gain more than participants that chronically restricted their energy intake.