Intermittent Fasting -The BBC Horizon Documentary

BBC Journalist Michael Mosley – Gave a 5:2 version of Intermittent Fasting a try.

It was great to see the BBC picking up on Intermittent Fasting this week in an hour long episode of Horizon. As a popular show, it will have been watched by millions of people.

When I posted this on Facebook Lyle McDonald shot back with this:

“Predicting the future: folks in the UK will now adopt IF’ing. They will starve all day and binge eat at night and wonder why they are still fat.”

Unfortunately, I think he’s right. People will miss the wood for the trees. There is a very clear nutritional hierarchy of importance for losing fat:

1. Calorie Intake vs Expenditure > 2. Macronutrient Split > … 3. Timing

Simply skipping breakfast is not going to get you magically lean and shredded. Never lose sight of this and don’t let your friends fall into the trap. I’d like to talk about this and a couple of other points raised in the documentary.

Nutritional Hierarchy of Importance for Fat-Loss/ Muscle Gain

In broad simple terms:

  1. Calorie intake vs expenditure controls whether you gain or lose weight.
  2. The macronutrient composition of your diet (carbs/fats/protein) controls the ratio of how much fat vs muscle is lost/gained.
  3. Nutrient timing, for the non-athlete, is a very distant third. -All the research so far backs this up.

This means that you are much better off putting your efforts into getting the right quantity of food and macronutrients for the day before stressing over the timing of things; it means you don’t have to always sprint home from the gym to get a post workout meal in your “anabolic window”; and most importantly it means that you can’t just stuff your face with reckless abandon, thinking that the fat burning during the morning fast will take care of it.

Yes, fasting – which is a part of nutrient timing don’t forget – can help with stubborn fat loss, but only when the other two things are firmly in place.

5:2 Intermittent Fasting vs Alternate Day Fasting ADF

The journalist did a “5:2” version of IF, where he ate just one small lunch (~500kCal) on two days of the week and then just ate whatever he wanted for the rest. Blood lipids improved and he lost a lot of fat. -Fairly painless, very simple, and gives the benefits of fasting.

Michael also tried Alternate Day Fasting (ADF). The scientist that has been studying people doing ADF said she found that as long as people hit their macro targets for the “fast day” despite the instruction to “eat whatever they wanted” on the other days people wouldn’t over-eat enough to undo the previous day’s good work. -There was still an overall calorie deficit.

In looking at ADF vs 5:2 it’s quite easy to see why, that’s 7 vs 4 fast days in a two week period which is a significantly greater deficit. Would this make ADF better for the average person then? Probably not. Michael said he found it too restrictive whereas the 5:2 was manageable. The key to success with the 5:2 though is to eat “normally” on your regular days rather than binge.

The above two methods work through calorie restriction. -Number 1 in our hierarchy. While this isn’t going to give a gym trainee the very best results (try the Leangains principles), they are free, very simple and perhaps a good introductory step or way to help out an overweight friend that wants to diet.

The part about IGF-1 (Insulin-like growth factor 1)

The documentary goes pretty heavily into extolling the benefits of IF as a life extension tool / way to prevent diseases by keeping IGF-1 low. Let’s not pretend here, the first thing you thought when you heard this wasn’t about living a happy and cancer-free life till you’re 90 was it? You thought, “Oh shit, does that mean it will affect my muscle gains?” Fortunately the answer I believe is no.

To quote Alan Aragon here,

“While it is true that IGF-1 can have powerful effects within the muscle, we also have to keep in mind that it’s the muscle-specific variant of IGF-1 – now commonly known as Mechano Growth Factor (MGF) – that is relevant to muscle anabolism. The circulating form has very little effect on skeletal muscle.”

Or as Reddit user Arrozconplantano put it quite succinctly,

“There is no evidence systemic IGF-1 causes hypertrophy.  It’s not worth thinking about.”

If this really concerns you then feel free to go and pester Martin or Alan about it. They are far smarter then me and will be able to give you better answers.

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We reached 1,000,000 blog hits today. -You guys made my mum cry. I hope you’re proud of yourselves.

I’ll have a guest post in the coming weeks by Beyond Brawn author Stuart McRobert.

Thanks for reading. -Andy.

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