Is It Time to Eat? A Surprisingly Important Question

‘Tis the season for making New Year’s resolutions.  Perhaps your resolutions include healthier eating and losing weight.  There is certainly plenty of info in my past articles on how to construct a healthy diet that will help you live longer and prevent chronic diseases. One element that may have been overlooked in all the scrutiny over what to eat is when to eat. There is growing evidence that restricting our eating to certain times of the day leads to more easily maintaining a healthy body weight.

Several authors and experts have been touting so-called “intermittent fasting,” which consists of only eating between the hours of 10 AM and 6 PM, for example. Another version of this approach involves eating normally five days per week, but essentially fasting (taking in less than 500 calories) on the other two days.  The idea behind this is that a more prolonged period without food discourages fat storage, and allows our body to switch its metabolism over to burn our stored fat supplies.

A recent study in mice (1) seems to support this idea. In this study, two groups of mice were allowed to eat as much as they wanted. One group had food available at all times, while the other group only had food available for a 12-hour period each day. The group with the more restrictive time ate about the same number of calories as the other group, and yet maintained a healthy body weight, while the unrestricted group became obese.  The time-restricted mice were even able to reverse obesity and prevent type-2 diabetes.  Cholesterol balance improved within two weeks, and blood sugar control improved within a few days.

A related study (2) showed how this intermittent fasting can change the composition of the gut microbiome.  A healthier blend of friendly intestinal bacteria leads to leaner body weight.

It’s too soon to translate these results directly to humans, but there have been some small human studies that point to the benefits of this approach.  One study found that intermittent fasting led to the same amount of fat loss as traditional calorie-restricted diets, but preserved much more healthy lean tissue. (3)

In a way, all of this seems to hearken back to traditional Chinese and Ayurvedic medicine: these systems used more poetic language to recommend against eating late into the evening or at night.  Whatever the reasoning, the outcome seems to be the same — better health when we pay more attention to eating at the right time of day.

Listen to an interview with one of the researchers:  You Are ‘When’ You Eat 

1.  Amandine Chaix, Amir Zarrinpar, Phuong Miu, Satchidananda Panda.  Time-Restricted Feeding Is a Preventative and Therapeutic Intervention against Diverse Nutritional Challenges.  DOI:

2.  Amir Zarrinpar, Amandine Chaix, Shibu Yooseph, Satchidananda Panda.  Diet and Feeding Pattern Affect the Diurnal Dynamics of the Gut Microbiome.  DOI:

3.  Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings.  Transl Res. 2014 Oct;164(4):302-11. doi: 10.1016/j.trsl.2014.05.013. Epub 2014 Jun 12.

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