Although the concept is tied into religious practices that date back thousands of years, the concept of intermittent fasting (IF) has been re-packaged as the 'new big thing' the last few years.
We're really talking about two strategies that get lumped together - actual fasting and time-restricted eating.
Fasting means you do not eat anything for a sustained period, often 24 hours or more.
Time-restricted eating is a long term strategy whereby you eat all your meals within an 8 hour window, avoiding food for the other 16.
Leading nutritionist Dr. Cate Shanahan recently reviewed the science behind how well IF works, and whether it might be beneficial for your long-term health and fitness goals.
For those who want the full rundown, you can access her blog post breaking down the research here.
If you simply want the highlights, here ya go!
- IF does not show any link to future eating disorders, as opponents of the strategy often argue.
- Yes, it leads to weight loss. However, Dr Cate quickly points out that literally any strategy where you restrict calories will lead to weight loss.
- No, it does not lead to more weight loss than your typical 'eat less calories per day' diet strategy.
- A problem with any prolonged calorie restriction is that it eats away at your lean body mass. Roughly 25% of all weight loss comes from losing the lean body mass you need to stay healthy and functional. IF does not offer an advantage here.
- Through research done to this point, the only advantage IF provides over other dietary strategies is that it can lower insulin sensitivity, which lessens your risk of developing diabetes.
The other logistical advantage it provides is simplicity.
Instead of shopping for foods with less calories or cooking healthier meals, you simply do nothing.
The caveat to all this research is that it is done by the American Heart Association, which strongly pushes vegetable oils as the healthiest fats to use when dieting.
Dr Cate would strongly argue that olive oil, avocado oil and dairy fats (butter, cream) are much better for you because they teach your body to burn fat more efficiently between meals.
Future research into IF using these fats may show very different results.
If you do currently use IF or one of its variations as a health strategy, know that it is currently unclear whether it is a more effective path to your long-term goals.
As with any other nutritional strategy, if you find something that works best for your health don't worry about all the noise.
Stick with what produces results.
