Time-restricted feeding plus resistance training in active females: a randomized trial (Tinsley et al., 2019)
Hate to be a buzzkill because this was actually a well-designed and well-conducted study.
I'm not a huge fan of intermittent fasting (IR) because it's usually shown to be no better than continuous energy restriction (CER) yet also require prolonged periods of severe energy restriction.
Also, if forced, I'd recommend starting with eTRF or an early dinner; the point being to extend the fasting window by starting it earlier in the day rather than ending it later -- there might actually be some metabolic benefits of this over isocaloric CER.
And in this case especially, athletes, who benefit from increased protein-feeding frequency which is removed from IF by design (although the authors attempted to partially bypass this by adding some HMB to an IF group).
#context: this wasn't eTRF. It was skipping breakfast. These weren't older insulin resistant people. They were young females with resistant training experience.
So, tell me again, how fasting induces growth hormone secretion which promotes the anabolic potential of skeletal muscle?
Breakfast and a late lunch instead?
The details: 8 weeks of supervised resistance training by a group of researchers who have experience with this. They know that TRF is not anabolic. In fact, they proved it in a previous study showing that resistance training increased muscle accretion in the control group but not in those assigned to skip breakfast.
And in this study, they tried to skew the odds and gave everyone protein shakes... absolutely no change whatsoever in fat-free mass.
The best the authors could say about it was "IF, in the form of TRF, did not attenuate RT adaptations in resistance-trained females." That's putting a positive spin on it. I'd say "resistance training and saturating levels of dietary protein are required to offset the catabolic effect of skipping breakfast." And further, if you actually want to increase muscle gains (as this study showed), supplements might be necessary, even if those supplements are diminishing the point of TRF*.
*The participants were supplied with HMB supplements to take while they were fasting. HMB is a leucine metabolite and thought to help muscle. A little bit. And it does, sometimes, although it's intended to mimic the 'not fasting state' which is categorically not TRF by definition. But anyway...
The exercise intervention was good, reducing the fasting aspect of intermittent fasting with HMB worked out OK, but overall no jaw-dropping effects were seen in this study.
That's all for now!
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