Intermittent fasting—in which patients cycle between periods of eating and fasting—has become an increasingly popular way to eat for better health. It can be an effective way to lose weight, control cholesterol, blood sugar and blood pressure and reduce the inflammation implicated in everything from heart disease to cancer. There is even research suggesting it can slow down aging and improve cognitive function.
The practice has been around for a long time, but it really caught on in 2012 after the BBC aired a documentary called Eat, Fast and Live Longer. Four years later, Dr. Jason Fung published his bestseller The Obesity Code, which laid out in convincing detail the science behind intermittent fasting’s effectiveness.
People think of it as a diet, but it should be viewed as more of a dieting pattern. By focusing not on calories, but the times you consume them, it changes how your body metabolizes food so that you end up burning more calories and more fat. When we eat carbohydrates, they are quickly broken down into sugar, which our cells use for energy. Any energy we don’t use gets stored in our fat cells. But sugar can only enter the fat cells with insulin, a hormone produced by the pancreas.
When we stop eating, our insulin levels go down and our fat cells can then release stored sugar to be used as energy. The reason intermittent fasting works is that it gives the body time for insulin levels to go down far enough, and long enough, to burn fat.
The 16/8 Protocol
Intermittent fasting protocols can be grouped into two categories: whole-day fasting and time-restricted feeding. Most doctor’s recommend patients do what is called a 16/8 protocol—also known as “early time restricted feeding”—in which they fast for 16 hours and eat only during an eight-hour window every day. This is a lot easier for many patients than trying to fast for a whole day.
First, patients should chart their food intake for two weeks so their doctors can identify the predominant nutrition they’re getting. The patients then think about their lifestyles and choose an eight-hour window for eating that will work for them. For some people that might be from 7 a.m. to 3 p.m., while for others it’s 11 a.m. to 7 p.m.
During the fasting time outside those hours, they can drink any non-caloric liquids, including coffee, tea or bone broth. Over time, if they’re struggling, the fasting window can be changed to get them better results.
In tandem with the fasting program, patients should exercise, avoid sugars and refined grains and eat plenty of fruits, vegetables, beans and whole grains. Also, it’s important that they avoid snacks, even during the eating period, to let their bodies burn fat between meals. This eating plan helps patients who struggle to control mindless snacking.
A Second Chance
Many patients who have tried every possible diet to lose weight or improve their health have not seen the desired results. Intermittent fasting is, for many, a second chance. Because it’s about when you eat, not what you eat, most people find it easy to sustain. Many patients average one to two pounds of weight loss per week. But the numbers are less important than the impact on their health.
Many have more energy, less inflammation and lower LDL cholesterol and triglycerides levels. But the most dramatic results have been with patients with diabetes. The fasting protocol reduces fluctuations in their blood sugar levels and many have been able to reduce their insulin.
In a recent study involving researchers from the University of Alabama-Birmingham and Louisiana State University, pre-diabetic men were divided into two groups, one restricted to eating six hours a day, the other to 12 hours. After five weeks, the six-hour group had significantly lower insulin levels and blood pressure, even though no one in either group lost a single pound.
A caveat to note, though, is that high-risk populations, such as pregnant women, elderly patients, anyone taking a lot of medications and anyone with an eating disorder, should consult a doctor before trying intermittent fasting. But intermittent fasting is recommended to anyone in reasonably good health who struggles with obesity, elevated blood sugar, elevated cholesterol, diabetes and hypertension and to anyone, really, who wants to improve their general well-being.
Christie Youssef, DO, is a board-certified osteopathic doctor of family medicine in MAPMG’s Fairfax family practice office. She sees patients at the Kaiser Permanente Fair Oaks Medical Center in Fairfax.