What if someone offered you an extra 4-5 hours per day to do what you wanted, while you got leaner?
What if they threw in some fat loss, feelings of euphoria and alertness?
OK what if you knew you could eat absolutely anything you wanted and still lose fat?
If you’ve guessed, I’m talking about ADF: Alternate Day Fasting.
Why is Alternate Day Fasting better than eating frequent meals?
With many biological mechanisms, we become desensitised to constant stimulus. Alternate day fasting allows you to reap the benefits of fasting and feeding in cycles while becoming more sensitive to both. During the fast, you’re burning fat, growth hormone is elevated, appetite is suppressed and mental focus is improved. During the feed, you’re more sensitive to insulin from the preceding fast, glycogen is replenished and nutrient partitioning is vastly improved. More on the mechanisms next week.
How do I start?
Simply fast for 24-36 hours. Drink lots of water, green tea and coffee during the fast. You can do this anything between once per week and every other day.
I personally favour the shorter fasts, but if you’re interested in additional health and neuroprotective benefits, fast for up to 36 hours. The health benefits will be discussed in part 2. When you break the fast, aim for between 1.5-2.5x the number of calories you would eat on a normal day, depending on your goal. So if your maintenance calories are 3000kcal, then eat between 4500kcal and 7500kcal on feeding days depending on your goal. If you’re fasting once or twice per week, adjust so that your calorie balance at the end of the week is where you want it to be.
But doesn’t your metabolism slow down when you don’t eat and you go into starvation mode?
Isn’t it a bit unnatural?
Yes it is. So is eating a Big Mac and Diet Coke. What’s your point?
The ‘it’s not natural’ argument does not fly. Unless you live naked in a cave and eat bits of tree, then the argument is void. Yes, ADF is unconventional and can be seen as a bit extreme. Therefore I do NOT advise this to anybody with a history of eating disorders or a strong emotional connection to food. As with all of the advice on this site, consult your physician before trying any new fitness endeavour including alternate day fasting.
Won’t I get too hungry, and it will affect my mental function?
Not for up to 48 hours of fasting. Personally I focus much better during the fasts. I don’t have to worry about my next meal, and I can just work away with a sharp focus. Colours are a bit brighter, sound is a bit clearer, and appetite is suppressed.
Isn’t this just a novel way of restricting calories?
No. It’s so much more than that. In fact, I believe you can lose fat while eating a calorie surplus using this protocol. Have you ever noticed the crazy muscle gains you make during the rebound period of a diet? Imagine that every day, constantly resensitising yourself to insulin.
You’re exaggerating, surely you don’t mean you can eat anything.
We’ve been eating up to 10,000kcal on feeding days, and up to 1500g carbs, and we still got leaner and stronger. You can push the limit, provided you’re training hard enough to earn your calories. See here for examples of what we ate.
Why does this work?
The main reason is described here by Weightology, in an absolutely fantastic article about insulin:
Underfeeding or fasting periods followed by overfeeding is superior to eating the same number of calories over the weekly period at a higher meal frequency because of the low insulin, increased ketone production, higher cortisol and growth hormone during the fast. These effects are great in moderation, but periods of higher insulin and overfeeding are required if you’re interested in preserving muscle mass. ADF combines the positive effects of both. However, just because insulin is low doesn’t mean you’re automatically burning fat, but it’s a useful correlation to make for the purpose of ADF.
But fat doesn’t affect insulin, so why can’t i have fat on fasting days?
Fat suppresses hormone sensitive lipase, which stops lipolysis. so you would be keeping insulin low but you would blunt the fat-burning effects of the fast. No food during the fast.
PS: Some of the studies linked in this article are critiqued in more detail by Martin Berkhan here in an article about fasting myths. Check it out.