Time to Eat

Time to Eat

Trim your waistline with intermittent fasting

By Krysten Godfrey Maddocks / Illustration By John R. Goodwin

For years, we’ve accepted the statement, “You are what you eat.” It turns out when you eat could have as significant an impact on your waistline. Some people can enjoy their favorite foods, if they don’t graze into the wee hours, by embracing intermittent fasting. For example, by keeping their eating within a six- or eight-hour time frame, they’re able to shed pounds without feeling deprived.

Popular diet programs such as Weight Watchers and Noom advertise their intermittent fasting plans, and many online wellness providers offer “quizzes” to help people determine what type of fasting plan they should follow. The International Food Information Council (IFIC) recently reported that intermittent fasting is more popular than a ketogenic (low-carb) or high-fat diet. The organization’s survey showed that about 10 percent of American adults use intermittent fasting as a diet. But many wonder, can it work for them?

Not all calories are created equal

Conventional math tells us that our weight is determined by the total number of calories we consume and burn, whether we consume our calories in one meal or throughout the day. But that’s not necessarily true, according to Dr. Robert Catania, director of metabolic and bariatric surgery at Southern New Hampshire Medical Center and director of Southern New Hampshire Weight Management in Nashua. Intermittent fasting can yield different results than conventional calorie restriction, he says. When you fast, you quickly use up glycogen stores or stored carbohydrates, forcing your body to tap into its fat stores for energy.

“One of the theories behind why intermittent fasting works is because you’re turning on your fat metabolism more often. You make less insulin and promote less energy storage and more energy burning,” Catania says.

When your body switches to fat-burning, the calories you take in becomes less important.

“You can actually eat about the same number of calories, but if you eat them at a different time of the day or on a different number of days of the week, it seems to have a benefit,” Catania says.

Food quality still matters

If you think you’ll be able to eat five Big Macs five days a week, fast for two days, and lose weight, you might be disappointed. It’s still important to pay attention to the quality of your diet, which means cutting out processed carbohydrates and getting enough fruit and vegetables. However, you can eat more of your favorite foods instead of measuring your portions.

“Intermittent fasting is a good place to start because people may not be able to commit to buying all fresh foods and vegetables, but they may be able to say, ‘you know what, I’ll stop eating after 6 p.m. and I won’t eat until the morning,’ ” he says. “The nice thing about intermittent fasting is that you don’t have to eat tiny portions.”

Drinking more water can also help you feel fuller and speed up your metabolism.

Picking the right plan

The type of intermittent eating plan you should follow has nothing to do with your blood type, age or body type. Many commercial diet plans and theories swear by the 18:6 program, where you restrict your eating window to six hours between noon and 6 p.m. Others suggest sticking to an eight-hour window. The plan you should try should be the plan that fits into your lifestyle, Catania says.

“You could come home and finish your last meal by 6 p.m., but many of my patients work second shift or multiple jobs. They may leave at 6 a.m. and return at 8 p.m. So for them, it might be easier to do a liquid fast or only one meal per day every third day,” he says.

Fasting isn’t safe for everybody

Waiting too long between meals can do more than make you “hangry” if you live with diabetes or other health conditions. Those who take sulfonylureas could experience hypoglycemia if their blood sugar levels get too low. Women who are pregnant or breastfeeding should also avoid intermittent fasting.

In some cases, calorie restriction can cause people to binge. You probably won’t achieve your weight loss goals if you overeat during your eating window. If you’re unsure if it’s right for you, discuss the benefits of intermittent fasting with your health care provider.

Results may vary

The intermittent fasting plan that ultimately works for your partner or co-worker might not work for you, even if you’re eating high-quality foods and adhering to your eating window. Catania says that some of his patients successfully lose weight through intermittent fasting and others do not.

“In my experience, men tend to do better with intermittent fasting than women,” he says. “I can’t tell you why biologically, but many guys come and say that all they did was change what time they ate and lost weight.”

In some cases, intermittent fasting does not help a patient lose weight, and while frustrating, that does not mean that the patient should lose hope.

“There are people who legitimately will do everything that we tell them to do and will not see any weight loss from this, and that’s really frustrating for people,” Catania says. “I talk to my patients about medications we can put them on. I let them know if it doesn’t work, we can try a different technique.”

Long-term success or short-term fix?

Because the reasons for an individual’s obesity diagnosis vary greatly, it’s unknown whether intermittent fasting will work for you in the long run — even if you’ve achieved a degree of success following it, says Dr. Hany Takla, bariatric surgeon and chair of the Department of Surgery at Wentworth-Douglass Hospital.

“We don’t know what happens if you aren’t giving your body what it needs and what the long-term effect of that is on your body,” he says. “Over time, intermittent fasting might not be as effective for you as when you first started. Your body has a defense mechanism against being deprived metabolically and physiologically.”

In other words, your body can acclimate to intermittent fasting, like it does if you stay on the same low-calorie diet or exercise program for too long. Or, if you discontinue fasting, you could experience the same “yo-yo” weight gain effect you might have experienced on previous diets.

For individuals who have a body mass index (BMI) over 35 with comorbidities such as diabetes or heart disease, or those who have a BMI of 40, surgery might provide more sustainable results.

“Bariatric surgery has been around since the 1960s, and people who’ve had gastric bypass have achieved great long-term success,” Takla says. “I tell my patients, when you’re at a certain BMI and have medical issues, these diets and medications work, but they are not as effective as surgery, and in the long term, they are not as sustainable. When they ask me about diets, I tell them to try it, but at a certain body mass index, dieting is not as effective as people think.”