By now, you have probably heard of intermittent fasting (IF). Perhaps you know someone who fasts or have even tried it yourself. When it comes to fad diets, IF has been around longer than many. According to one survey, intermittent fasting was the most popular weight-loss plan in 2018.

Studies have shown that, unlike many fad diets (grapefruit, cabbage soup!), intermittent fasting is safe. But the same studies show intermittent fasting is not any more effective for weight loss than any other diet that causes you eat less.

The idea behind intermittent fasting is that by restricting food, our bodies will more quickly and efficiently tap our fat stores for energy. While glucose from carbohydrates is our most direct fuel source, we burn fat for energy when glucose isn’t available. This happens even more during times of food deprivation.

When you think about it, fasting is evolutionarily embedded in our DNA. Think of the caveman who hunted for food. The caveman and his family didn’t eat three meals a day. When he brought home food, they ate. Then, depending on the prey available, they could go a day or two subsisting on plant-based food that could be gathered, or without eating at all. During the times of low food consumption, the caveman’s body used stored fuel (in fat cells) for energy. Eventually, his metabolism slowed to prevent him from starving until he killed more food.

In this way, our bodies are miraculously efficient and self-regulating. But intermittent fasting should be seen for what it is, a way for those of us interested in weight-loss to ingest fewer calories so that we use our stored fat for fuel. There is nothing magic about when you do or don’t eat if you burn more energy than you consume.

You could get similar results by skipping breakfast (yes, breakfast!) or lunch regularly as long as you don’t overeat at other meals. Replacing desserts (refined sugar) with complex carbs (fruit) will also save hundreds of calories a day. But if you like the structure that fasting provides, here are some of the most popular systems.

• 16/8 fasting – Eat for 8 hours and fast for 16 hours. Studies show this is the plan that most people can stick with over the long term.
• 5:2 approach – Eat regularly five days a week and limit yourself to one 500–600 calorie meal 2 days a week.  
• Eat-Stop-Eat – Fast for 24 hours once or twice a week. For example, fast from dinner one day until dinner the next day.
• Alternate day fasting – Fast every other day
• One meal a day – Eat one meal for the entire day with no snacking.  

While fasting, you can enjoy water and zero-calorie beverages such as black coffee and tea.

While eating, be mindful and focus on feeding your body healthy, nutritious foods. You’re not likely to lose weight or get healthier if you pack your feeding times with high-calorie junk food and foods with low nutritional value. This is true for any low-calorie diet. Eat nutrient-dense foods with adequate protein. Studies show that protein helps you keep hunger at bay and it is one of the best fuels to help your body function well. And remember that all low-calorie diets burn both fat and muscle. Weight-bearing exercise helps keep muscles strong and exercise that raises your heart rate will accelerate weight loss.