Fasting is the practice of abstaining from food for a period of time, while caloric restriction is a dietary regimen that simply reduces caloric intake. The greatest caloric restriction is no calories at all. Fasting has been branded the “next big weight loss fad” but has a long history throughout various spiritual traditions, practiced by Moses, Jesus, Muhammed, and Buddha. Today, about one in seven American adults report using some sort of fasting as a means to control body weight.
Rather than cutting calories day in and day out, what if, instead, you just ate as much as you wanted every other day? Or for only a few hours a day? Or what if you fasted two days a week or five days a month? These are all examples of intermittent fasting regimens, which I cover in my book How Not to Diet, and they may even be the way we were built to eat. Three meals every day may be a relatively novel behavior for our species. For millennia, our ancestors often may have consumed only one large meal a day or went several days at a time without food.
Intermittent fasting is often presented as a means of stressing our bodies—in a good way—and some forms may be safe and effective (and it’s safe to say cost-effective when it comes to your grocery bills), but apparently no more so for weight loss than continuous caloric restriction. However, combining intermittent-fasting regimens, such as early or midday time-restricted feeding with a healthier diet during the feeding windows, may prove to be particularly powerful. The weight may be worth the wait.
Our fasting for weight loss infographic compares the advantages and disadvantages of different types of fasting based on the latest evidence.
The information on this page has been compiled from Dr. Greger’s research. Sources for each video listed can be found by going to the video’s page and clicking on the Sources Cited tab. References may also be found at the back of his books.
Popular Videos for Fasting
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How to Boost FGF21 with Diet for Longevity
Fasting and exercise can boost the longevity hormone FGF21, but what can we eat—or avoid eating—to get similar effects?
Life Extension with FGF21
What can we do to boost the longevity hormone FGF21?
Fasting to Reverse Diabetes
By losing 15 percent of their body weight, nearly 90 percent of those who’ve had type 2 diabetes for less than four years can achieve remission.
Fasting for Post-Traumatic Brain Injury Headache
What effect do fasting and a plant-based diet have on TBI and migraines?
Fasting for Irritable Bowel Syndrome
More than half of IBS sufferers appear to have a form of atypical food allergy.
How to Boost Brain BDNF Levels for Depression Treatment
Fasting and exercise can raise BDNF levels in our brain, but this can also be achieved by eating and avoiding certain foods.
Fasting to Treat Depression
Caloric restriction can boost levels of brain-derived neurotrophic factor (BDNF), considered to play a critical role in mood disorders.
Fasting for Autoimmune Diseases
Various fasting regimens have been attempted for inflammatory autoimmune diseases such as lupus, ankylosing spondylitis, chronic urticaria, mixed connective-tissue disease, glomerulonephritis, and multiple sclerosis, as well as osteoarthritis and fibromyalgia.
Fasting for Rheumatoid Arthritis
Fasting, followed by a plant-based diet, is put to the test for autoimmune inflammatory joint disease.
The World’s Largest Fasting Study
Buchinger modified fasting is put to the test.