There are some who say that the combination of HIIT (High Intensity Interval Training) and intermittent fasting caused the “weight to just fall off.” Others say it is an inherently dangerous and even crazy combination. We know for sure that intermittent fasting is a research-proven way to reduce your insulin and glucose levels, and as a result, increase the weight you can lose by exercising. But how would it work with bike training? Would it help you to lose weight, or would it make it impossible for you to crank your pedals efficiently? This post, plus video, will help you decide if you want to give it a try.
What is Intermittent Fasting?
Basically, it just means having periods of not eating. It can also be called Intermittent Eating. So, in a way, we have all be doing it all our lives – it’s called sleeping. However, the catch is that you need to do it for longer than 8 hours. The most common pattern is to fast for 16 hours, and then have 8 hours within which you can eat. For example, have breakfast at 10:00 a.m., and then stop eating after 6:00 p.m.
This pattern can be combined with a specific diet, or you can just eat whatever you like.
Research showing the Effectiveness of Intermittent Fasting for Weight Loss
The idea is that when you fast, your insulin levels drop. Insulin is the hormone that allows glucose in your blood to enter your cells. The glucose then gives your cells the energy to function. In the absence of insulin, your cells still need energy to function. So, in the absence of insulin, your cells are more likely to release their stores of sugar or glycogen to create energy.
This theory has been backed up by very solid evidence. In a systematic review of 40 studies in 2015, reviewers concluded that intermittent fasting is in fact useful for weight loss, and also provides benefits to the cardiovascular system, by for example reducing blood pressure and lowering triglycerides. Crucially, intermittent fasting can encourage your body to draw on your fat cells for energy, rather than taking the easy out of utilizing glucose from carbs that you just ate.
Source: Seimon et al., “Do intermittent diets provide physiological benefits over continuous diets for weight loss? A systematic review of clinical trials.” In Journal of Molecular and Cellular Endocrinology, 15 December, 2015.
Weight Loss Success Stories with Intermittent Eating/Fasting
Anecdotally, we have a friend, Melinda who has been doing intermittent fasting for five months, eating and drinking whatever she likes during the allowed eating time. (Yes, including cheese cake!) As a result, she has lost 25 pounds. Melinda is glowing with health, and is in fact the reason that Maggie and I are now interested in trying intermittent fasting. Just look at her Before and After photos!
Melinda is not a cyclist, but she does hike, work out in the pool, and work a physical job every day. Her day includes an hour or more of exercise in the morning, long before she starts eating at 10.00 a.m.
Another Cycling Weight Loss Anecdote
One of the few times in my life when I lost weight without trying was when I was unknowingly doing intermittent fasting and cycling. Basically, cycling for an hour to get to work before having breakfast. Over a period of two years I lost about 40 pounds. Without once even thinking about dieting. However, that was with relatively short fasts – about 12 hours, I would guess, between dinner and breakfast. I now wonder if I would have done even better if I had stopped eating at 6:00 p.m. the previous evenings?
Related Post: 7 Steps to Lose Weight Cycling
Weight Loss Success Stories about Combing HIIT with Intermittent Fasting
Many of us now incorporate HIIT (high intensity interval training) into our cycling training. After all, there is a huge body of research that confirms that HIIT can increase your fitness and health gains substantially – in much less time than hours of endurance cycling.
Source: Roy, Brad A. et al. High-Intensity Interval Training. Efficient, Effective, and a Fun Way to Exercise. American College of Sports Medicine Health & Fitness Journal: May/June 2013. Volume 17, Issue 3.
This has made HIIT a lot more popular in recent years. But … can you safely combine HIIT with intermittent fasting. To many, it seems counter-intuitive, and maybe even dangerous, to ask your body to give peak bursts of effort (albeit in short bursts), while effectively running on an empty gas tank.
However, this has not stopped millions of people from trying it, searching for that magic bullet of rapid weight loss. And for some, it has worked. For example, teacher Sean Collins put on 60 pounds after finishing his tour with the Southwind Drum and Bugle Corps of Mobile, Alabama. First he got used to intermittent fasting with regular exercise, and then he upgraded his exercise regime by incorporating HIIT as well. He states that at that point:
“The weight just started to fall off. There’s no other way to put it.”
Collins lost a total of 114 pounds of fat, and gained a beautiful wife for good measure. But Collins was just 22 years old – if you are older than that, or have any health issues, please check with your doctor before making radical lifestyle changes.
Source: Men’s Health, HIIT and Intermittent Fasting Helped Me Lose More Than 100 Pounds. Jan. 16, 2021.
Video: Intermittent Fasting, Cycling, and Weight Loss
This video explores the issue of bike training while cycling. It is very interesting to watch.
Notice that in this video, they do not recommend the combination of intermittent fasting and high-intensity cycling training. However, for low to medium effort endurance rides, they do recommend training while fasting as a potential path to weight loss.
What is interesting is that if you click through to the video and read the comments, you will see that MANY viewers disagree vehemently. They make the point that if you want to do high-intensity bike training combined with intermittent fasting, you have to take a few weeks to a few months to let your body adapt. And MANY of them claim to have had major successes with weight loss by combining intermittent fasting and cycling.
Other interesting comments viewers made about intermittent fasting and weight loss:
Comments about Weight Loss
“Fasted training (also known as commuting 25 km to work and then having a breakfast :D) helped me lose 15 kg of weight couple years back, so it sure does something.”
“I’ve been doing 60–90 minute interval and hill workouts before breakfast, 3–4 times a week and have lost about 40 pounds over the last 4 months. I had plenty to lose, but training fasted has been great and I always seem to have just enough in the tank for hard efforts. I do bring a gel in case I go overboard and bonk.”
“I’ve been doing this for 2 years now and lost around 20 kg. I have built up to 20 hrs fast and 4 hr eating window, in effect one meal a day. I can train in fasted state no problem, regularly do 40 odd miles on black coffee only. Main benefit – no longer need to use small chainring! Eat quality food, avoid processed food. I don’t agree that you need glycogen to do intensive training, you will lose more weight if you train intensively in a fasted state.”
“Yes, intermittent fasting, with a mostly vegan diet/low calorie density, rich antioxidant dense foods, (minimal process foods/sugar) and regular pedaling has me down from 260 to 240.”
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Comment about High Intensity Training while Fasting
“I have done several 100-mile rides while fasting. Obviously one would need to build up to it. Also, I was able to do extreme high intensity while fasting. After some of those 100 mile rides, I was able to keep the fast going for 20+ hours.”
Comment about Race Performance and Training while Fasting
“If your goal isn’t a change in body composition but a change in race performance, here’s what I’ve heard: fasted rides can raise your fat utilization % at a constant (low) power relative to carbohydrates, which can help you in a race to “keep your powder dry” (i.e. save glycogen to cover attacks, etc.) From what I’ve heard, fasted rides should be no longer than 2 hours, after which you should eat to protect the immune system. And also, fasted rides should only be done a few times a week max. Following the fasted ride, eating fat-heavy foods (avocados, cheese, bacon, etc.) is a good way to accelerate the metabolic adaptation.”
If you do check out this video on YouTube, I would highly recommend subscribing to the GCN channel, as they produce a lot of excellent cycling videos.
Takeaways on Losing Weight using Intermittent Eating and Cycling
- First, this is something you should approach with caution, as with anything new. Anyone with any health issues should first consult their doctor.
- And as with all bike training, carry some snacks with you, in case you suddenly have a dire need for calories (the dreaded “bonk,” aka “hitting the wall”).
- It seems that for some, the best approach would be to stop eating at 6:00 p.m., and then do a long, relatively slow endurance ride the next morning (with snacks in your pockets, just in case!) Based on solid science and also on tons of anecdotal evidence, it seems that you would then be riding with very low levels of insulin, and that your body would be most likely to call on your supplies of fat to fuel the bike ride. Which would of course lead to weight loss over a period of time.
- That said, many people claim to be able to do more intense workouts while fasting, such as HIIT (High Intensity Interval Training). There are also many who argue that the combination of HIIT and intermittent fasting is like a magic bullet for weight loss. See for example the YouTube channel of Dr. Eric Berg. So, if you are a brave soul, you might want to go for faster weight loss by trying that (with snacks in your pockets!)
Good luck, and let us know how you do. We just started our intermittent fasting program today, and hope to have some good news to report back in a few month’s time.
Related Post: 7 Reasons to do High Intensity Interval Training (HIIT) on Your Bike – And How to Add Interval Training to Your Cycling
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