U-M dietitian Sue Ryskamp weighs in on intermittent fasting benefits, who it works best for and how to get started
Weight loss can be difficult, but could intermittent fasting help? This eating pattern, which features cycles of fasting and eating, is making headlines as research confirms it's not only what you eat, but when you eat, that matters in the struggle to lose weight.
During intermittent fasting, individuals use specific periods of eating — typically within an eight-to-10 hour window — to lose weight, says Michigan Medicine dietitian Sue Ryskamp, who sees patients at U-M's Frankel Cardiovascular Center.
The premise behind intermittent fasting is relatively simple, she says: "When our insulin levels go down far enough and for long enough, as they do during a fasting period, we're able burn off fat."
Insulin levels drop when a person is not consuming food. During a period of fasting, decreasing insulin levels cause cells to release stored glucose as energy. Repeating this process regularly, as with intermittent fasting, leads to weight loss. "In addition, this type of fasting often results in the consumption of fewer calories overall, which contributes to weight loss," Ryskamp says.
Intermittent fasting also allows the GI tract to rest and repair while in a state of fasting. "This is when your body is able to use fat stored in your cells as fuel, so you're burning fat instead of storing it, which leads to weight loss," says Ryskamp. "The results of recent studies look promising, especially when combined with exercise and a plant-based diet such as the Mediterranean diet."
A Harvard research study also reveals how intermittent fasting may slow the aging process through weight loss, lower blood pressure and reduced cholesterol.
So, is intermittent fasting actually healthy? Are there benefits? Pitfalls? Before deciding if it's right for you, read Ryskamp's Q&A below to get all your need-to-know questions answered.
Intermittent Fasting FAQ
How exactly does intermittent fasting work?
The diet works best when you stop eating at a certain time of the day and avoid eating at night altogether. That means no in-between or before-bed snacks. Although the time of eating will differ from person to person, many of my patients find success when they are eating between 10a.m. and 6p.m.
Is it a difficult diet to follow?
Intermittent fasting can be difficult, but as your body adjusts to a new way of consuming foods, the diet gets easier. The overall idea is to be more aware of what and when you're eating. It gives you limits and boundaries that many of my patients find helpful.
Along with intermittent fasting, we promote daily exercise, avoiding sugars, and choosing fruits, vegetables, beans, lentils, whole grains, lean proteins and healthy fats.
What is the most effective fasting time window?
Fat burning typically begins after approximately 12 hours of fasting and escalates between 16 and 24 hours of fasting.
How many days a week is this fasting recommended?
Typically, people fast for up to 16 hours each day. This is usually done by skipping breakfast in the morning after eating the final meal of the day on the previous day. There is also a pattern of intermittent fasting that involves going 24 hours without food up to two times per week.
How much can I eat during the eating period?
If your goal is to lose weight, aim for a calorie level that supports a weight loss of one to two pounds per week. On average, to lose one pound per week, you'll need to cut out 500 calories a day.
Are there certain beverages that should be consumed during the fasting period?
Water … and plenty of it. If you plan to engage in fasting, be sure to get lots of fluids in during the hours you're not eating solid food. Vegetable, chicken or bone broth can also be consumed. Soda and beverages containing caffeine should be avoided.
Besides weight loss, are there other benefits to intermittent fasting?
In addition to reduced body weight, this fasting can help lower cholesterol, improve glucose control, reduce liver fat and improve blood pressure. Patients tell me they have increased endurance, better motor coordination and improved sleep. Eating according to your circadian rhythm (eat day/sleep night) helps promote deep sleep. Studies have also shown that fasting, which leads to caloric restriction, increases the lifespan of even healthy people. Studies also suggest that fasting may reduce tumor growth and could help prevent recurrences of breast cancer.
Does it involve counting calories?
Not necessarily, but if you're cutting out snacks before bed and going for longer periods of time without eating, your calorie count will decline. Also, when you follow a mostly plant-based diet, you're consuming foods that are naturally lower in calories.
Who benefits most from intermittent fasting?
Intermittent fasting isn't for everyone. For individuals who've struggled to lose weight, this is another tool to have in their toolkit. In the end, it's about a person's lifestyle and the choices they make. They have to weigh the options and decide, "What's going to work for me?"
Are there certain medical conditions where intermittent fasting should be avoided?
People who are brittle diabetic, those with a history of eating disorders like anorexia and bulimia and pregnant or breastfeeding women should not attempt fasting unless under they are under close supervision of a doctor.
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