LCHF/ intermittent fasting weight loss goal

A few of my non cycling friends have touted keto/LCHF diet as a great method to help shift some weight over a sustained effort over a few months given their recent successfull weight loss. Of course it’s still a matter of fuel in < fuel out and each person is specific.

Previously, +5 years ago when weight resistance training my PT prescribed 40p40c20f on training days and 40p20c40f on rest days and I noticed some decent results over a 3 month period. However, I ALWAYS felt excessively hungry on training days and had large swings in energy. Non training days were actually okay.

I have a goal of shifting about 10kilos/22lbs so no mean feat but at 5"10 and ~94 kilos/207lbs it’s there to be shifted and no real time limit but 3-6 months is feasible.

Been cycling about 2 years and had a height Watt/Kilo of 2.9 last year after a week cycling summer holiday in Spain and solid training in the months leading up to it. Had built up stamina for centuries and bunch spins averaging low 30s kph (low 20s mph). However then moving/changing job/moving country happened (+8/9 kilos, -20 watts ftp and a lot less weekly miles).

Current diet/training plan:
I’ve wanted to try a mix of the 16/8 fasting regime during weekly work days, including a couple fasted ~90 mins tempo/as rides in the am and maybe 1 evening ~120 spin with hill repeats throughout the workweek.
Saturday Club Endurace ride of circa 100k and 1200m climbing to try and get some miles into the legs and get used to longer rides again. Sunday’s to be a short recovery spin. During the week I feel great. The 16/8 is working out easy to implement, I feel satiated throughout the day eating a clean version of LCHF and have very stable energy levels and find it easy to maintain calorie deficit.

However, on Saturdays spin I’m finding it hard to do anything over 2 hours without any carbs/glucose in the system (nuts etc just don’t cut it) so eventually usually have to stop at a cafe for something or tuck into the “emergency gels”. So I’m thinking of turning Saturday into a higher carb day with maybe a cheat meal (good quality pizza/pasta) post ride if progress isn’t being halted.

Has anyone had any similar experiences/advice/resources to share? Any study/articles for these diets don’t seem to include anything about +4 hour rides on a bike and while I know some endurance athletes are fully keto strict and “fat adapted” it doesn’t seem to work for me just yet. But then there’s suggestions about LCHF allowing duel fueling. But how and when to consume carbs then in this case?

Pre ride carbs/on ride carbs/post ride? High carb cheat meal better off the night before?

Thanks in advance,

Not sure what questions you are asking but here is my suggestion based on experimentation with this myself:

  1. Keto is simply a tool which might make it easier to lose weight.
  2. Losing weight still relies on calorie defecit
  3. Riding above zone 2 with no glucose in your system is difficult and unenjoyable, except if youre maybe highly adapted.
  4. I’d advocate for tracking calories, fuelling workouts correctly with glucose and losing weight through hard work on the bike and good habits in the kitchen. That way you can enjoy cycling at higher intensities AND lose weight

Hey @onemanpeloton thanks for post. I re edited with question. Somehow it posted first without me finishing.

Those highly adapted athletes are still the types doing ultra distance stuff at lower intensities.

I think on your Saturday rides you simply need to fuel up with a big bowl of oatmeal or whatever usually works for you. Just do the 16:8 fasting six days per week.

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I’ve combined intermittent fasting and cycling for nearly two years now. To great success. However, it took considerable time to work out an effective system.

My advice after much experimentation.

First, you can do far more time and intensity while fasted than you think. You cannot however, just start at hard 3hr rides. You have to slowly progress over many many months.

Your IF protocol, meaning the ratio of eating to fasting, 16/8, 20/4 etc is your own, it needs to work into your life and most importantly, you can change it at any time.

Personally, I generally hover around 18/6 on IF days. I do as many days of this a week as possible when trying to drop bodyfat. I can train fasted, up to 3hrs. Importantly, I do this at Z2 (zone 2), as I generally train in a semi polarized model. Meaning a vast majority of my riding is Z1/Z2.

The RPE (rate of perceived exertion) of fasted training is higher than fueled training. This is not really an issue when you are used to it. At higher intensities it becomes far more noticeable.

I believe, in the long run, it’s best to properly fuel any quality high intensity training. It feels easier, you perform better and you recover faster. However, if fat loss is your primary goal, the more fasted riding you do, the faster you burn fat.

Forget the cycling training for just a bit. Just think of it as a weekly total. Your aim is to burn more calories of energy than you consume per week. 1kg, a bit over 2lbs of bodyfat is approx 7700 calories. So, whatever deficit of that you have at the end of the week is, very approximately, how much bodyfat you’ve lost.

To lose a pound of bodyfat per week you need to run a 3350 calorie deficit. Here’s a sample week.

Monday - Rest - IF day - Deficit for the day 500
Tuesday - Hard workout, fueled - no deficit
Wednesday - Fasted Z2 - Deficit for the day 500
Thursday - Fasted Z2 - Deficit for the day 500
Friday - Fasted Z2 - Deficit for the day 500
Saturday - Hard workout, fueled - No deficit
Sunday - Long fasted ride - then rest of day off diet (cheat day) no deficit

Obviously, you can run a deficit on fueled days too, but personally I’ve found this unsustainable. My gut tells me that the extra food and increased glycogen storage on the Tues/Sat/Sun are what allows you to perform well on the fasted days as you’re never really totally depleting your glycogen stores.

If you’re really concerned that you need more intensity, you could add another hard workout on Thursday. Based on a week like this, you drop approx 2000 calories for the week. So, hypothetically you lose about 300 grams of fat. Maybe half a pound to a pound, depending on a billion other factors.

You then simply chose how much you want to push the needle. You can go right up to 1kg of fat loss a week, but this normally ends in a massive implosion. The manageable mid term number seems to be something around half a pound to a pound a week.

Once you reach your target bodyfat, you drop the daily deficit or add more fueled days. Getting that right and holding your perfect body weight etc is like a form of art. It’s complex and very personal. It just takes time and effort to figure out what works for you.

I still haven’t perfected that.

Finally, if you’re doing a TR plan or training with Threshold, Sweet Spot, V02 sprinkled in on many days… well that’s another whole can of worms.

Fat loss is best achieved in the base period. I normally hate to use pro riders as an example, but they all go through this.

Start your season with easy base training, combine this with reaching your body composition target, accept what bodyfat percentage you got to, then ride, race and train through the season at the weight you reached.

If you didn’t reach your target, don’t chase it while trying to improve or race. Start again the following year and do a better job. Play the long game.

The best practice is to not gain too much weight over the off season. Come into base training closer to your goal.

Don’t forget, we’re supposed to be doing this for fun. Don’t let losing bodyfat ruin the quality of your life.

Enjoy your riding, your training and just do the best you can.


@TheBandit many thanks for the detailed reply. Just 1 question:

In your sample plan you said for example Tuesday hard session no deficit. Are you saying for calories to equal base metabolic rate say 2,100 or base metabolic rate plus workout expenditure say 2,500?

On Saturday this could be in excess of 4000…! Hence the cheat day being aimed for Saturday at the minute!

Yes, basal metabolic rate plus workout expenditure on the two hard training days. You can experiment with this, run a small deficit, run neutral. Only you can really work out what is effective and what is sustainable.

It’s far from exact science, it’s virtually impossible to get it 100% correct. You’ll likely be a bit over or a bit under each day. I’ve also found that basal metabolic rate charts are often very optimistic. I had to drop nearly 400 calories off my estimate! You could be the same or the opposite.

That was just a sample week, it will depend on your lifestyle, social gatherings, weather and training load etc. I’ve also found being flexible with the weekly training and diet structure can help dramatically long term.

The extra calories on the two fueled workout days a week help keep your glycogen stores up. Obviously, the ideal situation would be to have your rest day also be your high calorie cheat day, with your hardest workout the following day. I sometimes do this. I normally have my cheat day on Sunday’s. It’s not the ideal diet or training solution at all. It’s a compromise. It’s better for my life and social interactions.

I generally have Monday as my rest day, as it is the most common practice here in NZ for cyclists. This allows me to slot into hard group rides etc on Tuesday’s if I feel like it. However, combining your hardest and longest training with your cheat day could be the ticket.

I’ve currently met my bodyfat / weight target which allows me two fueled workout days a week and a big cheat day on Sundays. The Sunday is a calorie surplus, by a large margin. The four fasted training days seem to counteract the two neutral fueled days and Sunday cheat day.

So far it’s working. It does require some mental gymnastics, but I kinda enjoy the math. That’s something I never thought I’d say…

The best strategy is to line up a test week and engage the program. Give it a few weeks. See how your training goes, do you sleep well, are you recovering etc.

Fat loss is very slow, the first week of IF or any carbohydrate restricting diet you will drop considerable water weight. Equally, this water retention will come back the second you increase your carbohydrate intake. You’ll see your weight fluctuate more during a week than normal. Ignore it. In fact, be very careful with weighing yourself.

You’re interested in long term trends. The scale can be a poor measurement device in the short term. What doesn’t lie is the tape measure. The rather old school tape measure of your waist is a remarkably reliable metric, as is the mirror :smile:


If you want to do Keto I would suggest Targeted Keto. Stay Keto until you plan on doing SS and above workouts (or even longer endurance rides). Consume carbs around and during those workouts. You typically will burn through what you have consumed since the body prefers glucose as a fuel source and when not riding go back to Keto (metabolic flexibility). Most of the time you will have a higher threshold for carbs during these type of workouts. This requires N=1 to see what your carb threshold will be.

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Been doing IF and keto for quite a long time now. My weight has generally been stable without any tracking, which I love, but there’s definitely a half-dozen pounds of flab around the midsection that really have to go. I’ve given up the IF and am trying to eat 3 or 4 protein-focused meals per day and it seems to be working. IF is definitely a tool for the toolbox, but if it’s stopped “working” consider switching it up.

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A running buddy did intermittent fasting after coming back from a back injury (8 months after fracture vertebra).
He did lost a ton a weight very quickly, but he couldn’t keep up with the intensity of training and would always ended up dead after wos.
Once he started eating again, he gain some of the weight back, but he could actually perform better during wos.

Point is. Eat what you like. Just dont over do it.

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The studies seem to show that IF is a hack - by limiting eating hours, you limit calories in a way that feels more manageable. One can do 5 days a week of IF if that allows one to train two hard sessions per week. Or change your window on those two days so that you properly eat before your workout. That might be tough for some people if they have to stop eating at 3pm that day. Or do a 10-12 hour eating window on those two days instead of an 8 hour window. You can be flexible. There is nothing magical about 8 hours over 10 hours.

Personally, I’ve struggled to lose that last 10-15 pounds. I’ve lost 20 over the last two years adjusting diet and have stalled. I’ve been thinking of trying a longer fast for health/longevity reasons. Maybe a side benefit would be losing 5 pounds of fat in the process. I’m thinking of something along the lines of a 5 day mimicking fast. I know it’s not compatible with training so that will be the hard part.

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That’s true, IF is basically just a method to run a calorie restriction. It’s far simpler for some people. Just delay your first meal each day. Start at 10am, move it to midday, then eventually to mid afternoon.

Pretty easy structure. I wouldn’t even categorize it as a ‘diet’. It’s just time restricted eating. You just eat food, like a regular human, preferably healthy etc. All you’re doing is literally delaying or eventually skipping breakfast and lunch it you get aggressive.

There are a few bonus health benefits however. Increased growth hormone production and greater autophagy, especially if you push it beyond 18hrs per day. Studies have proven that IF is not only as or more effective than continuous calorie restriction, it also reduces the amount of muscle loss.

It’s believed the increased growth hormone production while fasting helps retain muscle mass.

IF isn’t for everybody. It’s just one method of dropping body fat. There are many other options.


@TheBandit I love how you wrote exactly what I’ve come to understand during my 1 year of 35kg weight loss in 2017. I went completely overboard however with fasting continuously even during my HIT-days. I’m on the loooong journey of changing body composition and losing those final 5-7kg of fat that’s holding back my visible muscles :smiley: Great write-up however. Just wanted to say that.


@grenhall well done! 35kg in one year is some feat. Any tips outside of what @TheBandit has detailed above?

Did you try to reduce carbs specifically or just use time restricted eating/fasting a way to encourage lower caloric intake/adjust insulin sensitivity?

@TheBandit on a side note I’ve been directed to a Dr Jason Fung who has talks/books on IF, fasting as a whole and its benefits. It is mostly aimed at severe overweight diabetics but a very good resource to look at I have found.

I’ve also found a snippet from the TRP episode 194 which is useful.

While I have also found more material as per below. Specific responses to my original post would be greatly appreciated.

Some other links:

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You can read what I did here:


Cheers Aidan,

I’ve literally read nearly every study, listened to every podcast and consumed all the relevant videos on fasting. I’m now very much a case of possible confirmation and investment bias.

I’m 46, 60kgs and under 9% body fat. I wasn’t in this shape just a short while ago. I reached it by doing 90 days of long slow endurance riding, combined with IF. Most days 18/6, some 20/4. I even did a few 48hr fasts. These longer fasts, DO NOT work with training in any, way, shape or form. So, personally I am convinced that intermittent fasting is a powerful fat loss tool.

It is however important to always remain partially skeptical, even if confronted with considerable evidence. Currently, we’re living in a strange time where people are biased to the diet of their choice to almost fanatical levels.

Now, I am not claiming that IF is the best diet choice, or that it will make anybody a faster cyclist. In fact, I believe that unless used at the appropriate time and in a very diligent manner, IF will likely have a very detrimental effect on most cyclists power output.

Specifically to your post. I would certainly fuel your Saturday rides appropriately. Fuel before, during and after. I would also slightly increase your carbohydrate intake on the Friday night. This will ensure you have the adequate glycogen stores to perform at your best on the Saturday ride.

What you are attempting to do is, very difficult. It is far easier to engage a training and nutrition program specifically targeted at fat loss. This would reduce the expectation of fitness and performance gains.

Attempting to gain fitness, while dropping body fat is obviously, a far more complex balance. People will claim the opposite, but from my experience and observations, many cyclists struggle with weight, perpetually. They often see, little, or no substantial changes over many years. It is not as easy as many claim.

I maintain my stance that, it’s ideal to focus on one aspect at a time. Combine endurance riding with fat loss and harder, race or performance specific training, with the appropriate fueling strategy.

Ultimately, do these at entirely different stages of your yearly cycle. Not in the same week.

Play the long game…


I’m currently on a 2:1 fasting plan (two day eatting 1 day 12 hr fast) I usually ride a couple of hours after breaking fast. This I discover doing a ramp test after fasting is a no go. I’ve have noticed lower hrt rate after fasting.

keto is death, stay away