Thoughts on the Latest Study on Intermittent Fasting
It matters what you eat during the feeding window!
You’ve likely read articles or seen segments on morning talk shows about the latest study on Intermittent Fasting or Time Restricted Feeding, declaring “It doesn’t work”! As with all studies, we need to look at the data and not just what the researchers concluded.
When analyzing a study it’s important to consider the sample size, the length of time, was it controlled and randomized, who is backing the study, what is the goal of study and what are they measuring. This study was controlled, started with 116 participants, lasted 12 weeks and the goal was to measure weight loss. More of the participants that completed the study were in the control group (57 vs. 29), which were told to eat three meals per day and as many snacks as they wanted. The test or Time Restricted (TE) group were told to eat all their meals between noon and 8:00 pm. They were allowed to eat anything they wanted, at unlimited quantities. The TE group did lose more weight but it was not significant and most of it was lean mass. We definitely want to keep our lean mass and lose fat mass! This was surprising even to those running the studies as previous studies have shown the opposite.
The loss of lean mass is concerning but I think that can be attributed to the way the TE group approached intermittent fasting. If they were eating the SAD (standard American diet) before and during the study, I would not expect health markers to improve at any significant level. In addition, if they are completely sedentary then lean mass will likely contribute to some of the weight loss.
This is why I structure my Fast + Reset program with a plan for healthy eating during the feeding window. This is so important and what most participants value the most. In addition, I encourage movement and exercise during the program with guidance on the best type of exercise to enjoy during the fasting and feeding windows. Another very important piece is that I advise participants to NOT fast every day. This will slow metabolism and can lead to muscle wasting. Many participants enroll in the program with a history of “sort of fasting” (coffee with cream or MCT oil, ketones, etc.) on a regular basis. This can have a negative impact on hormone levels, particularly with women. I help participants understand how to do a few days of intentional fasting, with a focus on healthy food and activity to get the best health benefits from fasting, including autophagy, which was not measured in this study. I encourage participants to eat regularly, focusing on healthy eating during a 12 hour window and don’t fast often. It’s like endurance training… don’t spend all your time in the gray zone.