How long is the fast?
Here's where the diet gets really personal. Glassman says the most popular version of Intermittent Fasting involves fitting in all your daily food consumption into an eight-hour window. Then, you fast for 16 hours. "For example, you could eat between 10:00 a.m. and 6:00 p.m. every day and fast between 6:00 p.m. and 10:00 a.m. (including the hours you’re asleep)."
Another version, explains nutrition expert Brooke Alpert, MS, RD, CDN., is the 5:2 Diet. She says this consists of eating regularly five days a week, and then eating around 500 calories or less for two days in a week. "In my book, The Diet Detox, I actually recommend a modified version of IF, asking for a 12-14 hour fasting window from dinner until the next morning's breakfast. This is called Early Time Restricted Feeding, eTRF, and it’s shown to have close to the same results as longer fasts, but it’s a plan that more people can be successful on."
Why would someone start an Intermittent Fasting Diet?
One of the most popular reasons people try this diet is for weight loss, Glassman says. "The most basic reason it can work for that purpose is that you’re most likely going to end up eating less when restricting calories to set time periods," she adds. "Fasting can also reprogram your metabolism. When your body isn’t getting the energy it needs from food, it turns to its other fuel source: stored fat. By breaking down more fat and shrinking the size of fat cells, you end up with fat loss, and as a result, weight loss."
It's not just about losing weight. Health expert Naomi Whittel says Intermittent Fasting is an activator of a thing called autophagy. Whittel says it's, "a biological process that comes from the Greek, 'auto' meaning ‘self’ and 'phagy' meaning ‘to eat,’ and it's literally the way your cells self-cannibalize." This is when your cells eat away the waste that leads to visible signs of aging. It's basically your body's way of cleansing itself.
What should you be eating during the food-consumption window?
Intermittent Fasting doesn't give you an excuse to only eat junk food or sweets. "If you do think it might work for you, make sure you’re still eating in a healthy way, AKA getting all of the proper nutrients from the calories you are consuming!" says Glassman. "Focusing on real, whole foods and skipping the junk will prevent nutrient deficiencies."
She also adds that you should still be getting the same amount of calories you need in a day of regularly-timed eating, though the amount you eat might naturally drop. Alpert suggests quality protein and fiber-rich plates during your eating window.
Should you alter your workouts?
This answer depends on how much fasting changes your normal exercise routine. Glassman says if you usually work out in the morning in a fasted state, it shouldn't change anything for you. "However if you can’t get through your morning after your workout and then fasting until 2 p.m., then IF may not be the best option for you. If you normally work out at night and it would fall into your eating hours, it again might not affect anything at all!"
What are the potential concerns of Intermittent Fasting?
Every diet has its downsides. "Confining yourself to a specific way of eating for a short time can also lead you down a long road of yo-yo dieting, and some argue fasting can lead to disordered eating," warns Glassman.
If you have blood sugar issues, Intermittent Fasting might not be the best eating plan for you, either. For someone who is diabetic, Alpert says talking to a doctor and getting the eating plan approved is absolutely key. In addition, she says that she wouldn't recommend it to anyone who has a history of an eating disorder or anyone who is pregnant.
Is fasting better than eating lots of small, healthy meals?
"Both can be effective," says Alpert. "It really depends on the person, their history, and their eating preference. For some people, IF can set them up to overeat when they do eat and to make poor choices. For others, they are able to happily reach for something healthy. Again, this is a personal decision."
This article originally appeared on InStyle U.S.