re: Can anyone confirm some IF broscience with anecdotal evidence?

Best study to date on IF was released this week by the guys at Texas Tech specifically Dr Grant Tinsley. LINK

Menno did a good summary of it

quote:

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No study has very rigorously examined the effect of intermittent fasting on muscle growth. Until now. Grant Tinsley et al. (2019) is arguably the best-controlled study on intermittent fasting to date.

The researchers randomized female strength trainees into 2 groups. Both groups were given the same macros intended to establish a small energy deficit and both groups supplemented whey protein.

1. The IF group consumed all food between 12:00 and 20:00 h and trained sometime in this window (so no fasted training and they had post-workout nutrition).

2. Another IF group with the same protocol consumed HMB.

3. The control group consumed an early breakfast and could eat all day, ending up with a ~13 hour eating window instead of the ~8 hour IF eating window.

The IF and control group achieved similar results with no significant differences between groups in muscle growth (increase in fat-free mass and muscle thickness of the elbow flexors and quads), fat loss or strength development (6 measures including 1RM bench press and leg press). See attached figure for an overview of the results.

One exception: the IF group supplementing HBM achieved less quadriceps growth (significant in PP, strong trend in ITT).

Results were the same in the total intention-to-treat analysis (ITT) and the stricter per-protocol (PP) analysis.

Resting energy expenditure and standard health biomarkers also didn’t differ between groups, except for pulse wave velocity (measure of arterial stiffness), which was all over the place, so I don’t think we can reliably interpret that.

Mood states, sleep quality and eating behaviors also didn’t differ significantly between groups.

These findings suggest IF with an 8-hour eating window does not affect our body composition, training progression or basically anything at all.

However, this study was not sufficiently statistically powered to detect small differences. Out of the 40 initial participants, only 31 remained by the end of the study and only 24 followed the study per protocol.

While macro intakes did not significantly differ between groups in the total sample or the per-protocol participants, there was an over 200 kcal difference in energy intake between groups in the per-protocol analysis and a strong trend (p = 0.09) for carbohydrate intake to differ between groups. The respiratory quotient also differed between groups, suggesting macronutrient intakes differed (significant in PP, p = 0.1 in ITT).

Take-home messages:
- Intermittent fasting won't majorly affect your gains, at least as long as you don't train fasted and have proper post-workout nutrition.
- HMB still sucks.
- Women can be successful on IF diets just like men, although no gender difference was formally investigated in this study.

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I do not agree with Menno on everything and neither does Grant. Specifically the per protocol group did show greater fatloss. Menno automatically attributed it to the IF group taking in less calories since the study was based on reporting and not done in a controlled setting. I and Dr Grant both believe it needs further research is needed to prove one way or the other. There is some promise to IF to possibly burn more bodyfat than isocaloric.


As far as the autophagy question, more than half of the effects come from the caloric deficit and using body fat for fuel. At least based on the studies I have seen. Dry fasting accelerates these effects but it is still dangerous.