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Intermittent Fasting: Is it Hype or Is There Science Behind It?

Intermittent Fasting: Is it Hype or Is There Science Behind It?

Intermittent fasting (IF) is a form of time-restricted fasting that involves consuming foods during a specific time window and fasting for the remaining hours of the day. The most popular is the 16:8 plan, where people cease eating in the early evening and do not resume until late the next morning (approximately a 16-hour fast, and an 8-hour eating window). There are no restrictions on the types or amounts of food a person can eat during the 8-hour window. This flexibility makes the plan relatively easy to follow.

Within the 8-hour timeframe, people can eat their meals and snacks as they please, though eating at regularly spaced intervals is important to prevent blood sugar peaks and dips and to avoid excessive hunger.

Although IF plans do not specify which foods to eat and avoid, it is beneficial to focus on eating nutrient-dense foods and to limit junk food consumption.

A balanced diet includes:

  • Fruits and vegetables
  • Whole grains, including quinoa, brown rice, oats, and barley
  • Lean protein sources, such as poultry, fish, beans, lentils, tofu, nuts, seeds, low-fat cottage cheese, and eggs
  • Healthy fats from fatty fish, olives, olive oil, coconuts, avocados, nuts, and seeds

Importantly, fruits, vegetables, and whole grains are high in fiber, so they can help keep a person feeling satisfied during fasting hours. Consuming healthy fats and proteins can also lead to feelings of satiety.

Beverages are an important dietary focus for those following the 16:8 plan. Drinking water and other calorie-free drinks throughout the day can aid in feeling satisfied during the fasting period, as people often mistake thirst for hunger.

What Does the Science Say?

The research on IF indicates that it may provide the following benefits:

  • Weight loss
  • A reduced risk of chronic health conditions related to obesity
Weight Loss:

Having a set eating period can help limit the number of calories a person consumes. In a 2015 systematic review of 40 different studies on IF, it was concluded that the plan is useful for weight reduction. In 2017, a 1-year study was published that compared IF and a typical calorie restriction diet. There was no significant difference seen between the two groups for weight loss or other health markers. Most of the current research suggests that IF may be an effective weight management strategy.


The primary risk factor for type 2 diabetes is being overweight or obese. Some studies have shown that IF can lower blood glucose and insulin levels in people at risk for diabetes. Research among adults in this group also found that IF could reduce insulin sensitivity.

In addition, IF may drive weight loss by decreasing insulin levels, which drop during periods of fasting, consequently causing cells to release their glucose stores for energy. As IF can lead to an overall decrease in calorie consumption, it is likely that it will aid weight loss, as well.

Generally, studies suggest that IF is as effective as traditional calorie restriction methods when it comes to reducing weight and body fat. It may also be easier to stick to than traditional methods of weight loss, such as calorie restriction. Anything we can do to support our patients' weight loss efforts is helpful. Weight reduction is difficult for many of our patients and there are strong data that reducing obesity in itself has substantial health benefits.


Filed under: Health Policy and Trends, Miscellaneous

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