Most Recent

Is Intermittent Fasting Responsible for Weight Loss?

Is Intermittent Fasting Responsible for Weight Loss?

A study from Jama Internal Medicine shows us the results of time restricted eating, plus my views on studies in the future for circadian fasting

Have you ever wondered if intermittent fasting is responsible for your weight loss or if there is potential to lose weight if you started it? A randomized clinical trial was done at the Jama Internal Medicine (JIM) to see if time restricted eating would be beneficial to humans. While the results are still up for debate and more studies need to be done, it’s an important topic to discuss. Here are the key details of the study.

The trial

The trial took two groups of American men and women aged 18 to 64 years with a body mass index of 27 to 43. One group was asked to practice consistent meal timing (CMT) and was instructed to eat three structured meals per day. Snacking between meals was permitted. The second group was instructed to follow a time-restricted eating (TRE) where they would eat as much as they desired from 12:00 P.M. until 8:00 P.M. and completely abstain from all caloric intake from 8:00 P.M. until 12:00 P.M. the following day. Non-caloric beverages, like black coffee or green tea, were permitted outside the eating window. JIM chose this timing because they felt that dinner was a more social meal compared to breakfast and people would have a harder time fasting through dinner. They also decided that they were going to have a control arm and they were going to use 12 weeks to get results. They enrolled 141 random patients—72 who followed the CMT timing and 69 people who would follow the TRE. Out of this, 25 participants never submitted their data and only 105 completed the 12-week protocol. Data was collected at UCSP for 50 people who lived in San Francisco, California while the rest submitted their details and statistics via a custom mobile study application.

They found that in 12 weeks, the time restricted eating group lost .94 kilograms, which was lower than the baseline, but the consistent meal timing group also lost .68 kilograms, which equates to the conclusion that the difference in the results between each group were not statistically significant. While both groups lost weight and the TRE group did lose more weight, it was not enough. In addition, the study found that the TRE group may have lost a more lean mass than those that were following the CMT. 

The summary is that we need more studies done because there was really no advantage to time restricted eating when compared to a proper control group like consistent meal timing. This also means that we need to perform more studies on the details of the actual weight loss results from intermittent fasting, including but not limited to fat, muscle, water, etc. 


Lastly, there is more to learn from this study and we need to do more trials on this topic. There are two reasons for this:Time-restricted eating (TRE) is only one type of intermittent fasting (IF), which involves consistent fasting and eating periods within a 24-hour cycle. Different types of IF reap different benefits for different parts of our minds and bodies. To understand each type of IF and their benefits, we need more studies and trials.

Since circadian fasting is different from traditional fasting, it would be helpful to ensure that we asked study subjects to eat an earlier dinner and have participants eat breakfast since the results may vary greatly depending on the time of day a human stops eating.

Read the full research paper here.