Intermittent fasting: What you need to know

Intermittent fasting may sound like the perfect weight loss tool. It often includes every foodie’s dream instruction: “You can eat whatever you want!”

That’s because it can appear that the only requirement for this “eating pattern,” as it’s sometimes called, is that for many hours of each day, you don’t eat anything at all.

For example, some programs suggest fasting for 16 hours (6 p.m.-10 a.m.) and eating whatever you want the rest of the time. Other plans suggest fasting for two 24-hour periods, twice a week. The rest of the week has no restrictions on time or food.

But the reality is, for intermittent fasting to have any benefits, you have to eat mostly healthy foods. And you may not lose any more weight than you would on a regular plant-based or Mediterranean diet.

Why do intermittent fasting?

Studies show that the technique can improve blood sugar control and promote weight loss. Studies on rats also showed improvement in learning, memory and lifespan.

What’s not clear is if those health benefits came from the fasting or simply from losing weight.

Our expert says intermittent fasting may not be a good choice for long-term health or weight loss.

“It’s not a solution to all the long-term challenges that someone may be having, like not exercising or not eating healthy foods.” says Erma Levy, a research dietitian in Behavioral Science.

Addressing these core challenges is a better way to maintain healthy blood sugar levels, Levy says.

Intermittent fasting for weight loss?

If fasting leads you to eat less, then it is likely you will lose weight. But what’s less likely is that you will be able to keep eating this way and maintain a healthy weight.

“There could be some pros to intermittent fasting if you’re choosing healthy foods during the eating time, but long term, you’re unlikely to be able to keep the weight off because fasting is so hard to maintain,” says Levy.

As a result, your weight will probably come back to its pre-diet resting place. You will not get the health benefits of losing weight, like lowering your risk for cancer, heart disease and diabetes.

Intermittent fasting for a healthy lifestyle?

Intermittent fasting doesn't help you make healthy food choices, and it can hold you back from being physically active. And staying active is one of the most important things you can do to lower your cancer risk.

Our bodies are designed to eat at regular intervals to perform at their best. Fasting can lead to light-headedness and low energy, and that can make it harder to exercise.

Real weight loss and lower disease risk require lifestyle changes made slowly over time for them to stick. You might start by adding two to three extra servings of vegetables a week. Then you might switch from red meat to grilled chicken for two servings the next week, and progress from there.

“It takes time to turn negative behavior into something positive,” says Levy.

The ideal diet: Plant-based with exercise

The following tips are the foundation for long-term weight management and healthy eating.

Eat a plant-based diet.  Fill two-thirds or more of your plate with plant foods like vegetables, fruits and whole grains. Fill the remaining 1/3 or less with lean protein like chicken or fish.

Limit red meat and avoid processed meat. Eat no more than 18 ounces of cooked red meat per week. Red meat includes beef, pork and lamb. Processed meat includes bacon, deli meat and hot dogs. 

Avoid alcohol. Research shows that drinking even a small amount of alcohol increases your chances of developing oral, breast and liver cancers. The Centers for Disease Control and Prevention recommends that women have no more than one drink per day and men have no more than two drinks per day. A drink is defined as 12 ounces of beer, 5 ounces of wine or 1.5 ounces of liquor.

And to give your health and your waistline a real assist, aim for at least 150 minutes of moderate exercise or 75 minutes of vigorous exercise each week.