When I first found out about the ketogenic diet (lovingly, aka, keto diet) in 2012, I felt I had found the holy grail of diets. It promised fat loss, sustained energy levels, disease prevention, and superhuman powers (not really, but it’ll feel that way)! I thought to myself, I’m set on diet, time to focus on upgrading the rest of my life!
This is why a few years later when I started hearing notable speakers like Dr. Jason Fung talk about the benefits of Intermittent Fasting (IF), I struggled to understand why my precious keto diet wasn’t the diet “to rule them all”. Like any good scientist, I first emotionally rejected it, and then eventually gritted my teeth and dug into the science.
Turns out, there’s a lot of similarities between the two. I won’t go into detail on the keto diet and all it entails since those details can be found in my other blog post, Ketogenic Diet and You. Here I’ll focus on IF, the metabolic changes that happen, and then compare it to the ketogenic diet so we can finally settle the question, which is better?!
Well first, what is the exact length of an intermittent fast? Several studies have shown that the largest decrease in blood insulin (read: blood sugar) occurs about 18-24 hours postprandial (after last meal). This is also when fat mobilization increases the most; your body is switching from sugar to fat burning at this point!
Figure 1: Data Taken from “Progressive alterations in lipid and glucose metabolism during short-term fasting in young adult men”
During an intermittent fast, your body undergoes several biochemical changes. These include:
- Lowered Blood Glucose and Insulin Levels
- Improved fat oxidation and ketone production
- Upregulated Human Growth Hormone (HGH)
- Reduction in Inflammatory Markers
As it turns out, a ketogenic diet is a fasting-mimicking diet. Once you’ve depleted all your carbohydrate stores via a Low Carb High Fat (LCHF) your body actually starts to act as if it were in a fasted state! A cascade of biochemical changes occur which turn you into an efficient fat-burning machine, with loads of mental clarity to boot.
For those of you wanting to get started with IF, many researchers suggest starting by switching to an LCHF first. This will get your body efficiently mobilizing fats prior to doing a full fast, and ultimately reduce some of the discomforts associated with beginning IF such as irritability and hunger.
So there you have it! The ketogenic or LCHF diets are simply a sneaky way to get your body believing it’s in a fasted state! Whether you choose to simply change your macro consumption or restrict your eating window, rest assured you’re making the right moves to help you Live Better, Longer!