Losing 3 to 5 pounds a week may sound like a good thing, until you learn you'll only be eating 500 calories a day. Very low-calorie diets can help you lose weight fast, but limiting your intake to such extremes for any length of time can be dangerous, which is why some people may only do it once or twice a week as a weight-loss strategy.
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Before you start any weight-loss diet, especially one that limits your intake to 500 calories a day, even on an intermittent basis, consult your doctor to discuss benefits, risks and other alternatives.
The Basics of a 500-Calorie Diet
It's very difficult to get all the nutrients your body needs for good health on only 500 calories a day. Diets that provide fewer than 800 calories are called very low-calorie diets, or VLCDs. They generally consist of a liquid supplement that provides an adequate amount of protein, plus vitamins and minerals to help meet nutritional needs.
VLCDs are usually reserved for people who are severely obese, and a person on such a diet requires close monitoring by his or her doctor. VLCDs may be used when an individual has reached a weight loss plateau or for someone who is not a candidate for weight loss surgery. The diets are only meant to be followed short term, no more than 12 weeks.
When you eat so few calories your body goes into what's often referred to as "starvation mode." Thyroid hormones, which are hormones that regulate your metabolism, decrease to help limit calorie burning. While your body does burn fat when you reduce your intake, it also breaks down your muscle. And because you're eating so little on your 500-calorie diet and not getting enough protein, you'll continue to burn muscle for fuel.
That being said, intermittent fasting is a recent diet trend that alternates between periods of normal eating and fasting to help promote weight loss. Some of these diets count a 500-calorie eating day as fasting. Although you still need to discuss the diet with your doctor, limiting your intake to 500 calories one or two days a week may allow you to use real food instead of a liquid supplement, since you'll be able to get the nutrients you need on the other days of the week.
In any event, you want to make wise food choices when you're limiting your intake and include low-calorie, nutrient-dense foods periodically throughout the day. And fill in with calorie-free foods and drinks such as sugar-free gelatin and ice pops, fat-free broth, black coffee, plain tea and sugar-free lemonade to help control hunger and maintain hydration.
Intermittent-Fasting and the 500-Calorie Diet
Not only is it easier to limit your intake to 500 calories only a couple of times a week, but it may also serve as an alternative way for you to lose weight, especially around your middle, according to a 2014 review paper published in Translational Research.
This review found that although people lost more weight on regular calorie-restricted diets, intermittent fasting was just as effective at helping decrease belly fat. Restricting your intake for short periods of time causes your body to release hormones that help you burn fat and build muscle. It also releases hormones that give your metabolism a little boost too.
What You Might Eat for Breakfast
To help keep hunger away when limiting your calorie intake to 500 calories, include a source of protein at each meal. Protein is more satiating than both carbs and fat. Also, try to eat about the same amount — about 160 calories — at each meal for a balance of energy throughout the day.
For breakfast, 1/2 cup of fat-free cottage cheese with a small banana makes a good option, or, have a hard-boiled egg with a slice of whole-wheat dry toast. A 3/4 cup serving of whole-grain unsweetened ready-to-eat cereal with 1 cup of nonfat milk also makes a good low-cal breakfast.
Sample Lunch Meals
For lunch, you can fill up on 3 ounces of grilled chicken set on top of 3 cups of mixed greens with red wine vinegar added for flavor. A 6-ounce container of nonfat Greek yogurt with 1 cup of fresh blueberries also makes a good high-protein lunch option on a VLCD plan. Or, you can roll slices of deli turkey — up to 2 ounces — in lettuce leaves smeared with mustard, and serve it with two whole-grain fat-free crackers.
Ideas for Dinner
Fifteen large boiled shrimp garnished with 1 tablespoon of cocktail sauce and 1 cup of steamed broccoli may help tide you over until the morning. Or, make a stir-fry with 3 cups of vegetables such as bok choy, carrots, mung bean sprouts and celery and 1/2 cup of cubed tofu.
To save calories, skip the oil and saute in 2 tablespoons of broth and a teaspoon or two of low-sodium soy sauce. Have breakfast for dinner with a four egg white omelette filled with 1/2 cup of spinach, 1/2 cup of mushrooms and 1/2 ounce of low-fat cheddar cheese.
If you have a medical condition such as diabetes or low blood pressure, or if you take prescription medications, you shouldn't fast without your doctor's approval. Long term calorie restriction with a VLCD can result in hair loss, cold intolerance, headache, fatigue, and dizziness, according to a 2006 review article published in Obesity.
Intermittent fasting is also not recommended for people who are underweight or women who are pregnant or nursing. Children and adolescents should not eat a VLCD and individuals with a pre-existing eating disorder should not attempt intermittent fasting.