Riding Zone 2 for extra fat-burning

Hi all.

This is my first TrainerRoad post so if I am doing anything wrong please let me know.

TLDR: Will doing long Sone 2 workouts each day make it possible to do some higher calorie deficit than let’s say 500kcal on a normal diet with some training?

Anyway, here it goes. First part is Background.

Last season I did a self-coached/planed training plan for a 150km MTB for this summer. Finished the race and was happy with the result. Now, two months ago in august, I decided to lose some weight since I had no other goal set up before next year. My starting weight was 73-74kg, 180cm, and an ftp of 337 tested at the start of the Sweet Spot 1 HV plan. That was down from 376 before the summer tested with a 20min power test. That was a bit of a let-down, but accurate since the following workouts (all done on the trainer) were challenging enough. While doing the SSB HV plan 1 and 2 I decided to do some strength as well, so I did 1-2 sessions each week. And weight loss has an important part done in the kitchen, so I counted all my daily intake of food using the MyFitnessPal and set a deficit of between 500 and 1000 kcal each day. This meant I had done some nutritional timing to be fuelled for my workouts. I have now completed the Sweet Spot Base Hight Volume 1 and 2 with only eating before the workouts, and only using water during the sessions. That last part was difficult in the start since I was reliant on sugar during the rides earlier this year, but now I can do 2h sweet spot only water no problem which is nice. Now after these 12 weeks I have gone down to around 69kg. I have gained some muscle and strength but will take a two-week break before I do another weight loss period before Christmas. Also, FTP has gone up in-between the two plans to 349 and likely up some more if I tested now at the end of this plan.

The next part is the plan for the second Loss-Period.

For this period, I have a goal of loosing around 4kg, going from 69kg to 65kg. I am not sure if I should do a solid Sone 2 block of six week or continue with a General build plan with some intervals. I have always wondered if I can “Speed up” the process of loosing weight by doing more low intensity training. Let’s say on a normal day I can do a deficit of 500kcal and still be mentally good for my day and workouts. Could I then do a longer 4 hours sone 2 workout and have the deficit even higher, let’s say 2000kcal since I will be burning more fat during this low intensity workout and thus lose weight faster? I might be completely wrong here, so please let me know. My goal now is NOT to gain watts on the ftp but losing weight (fat) to reach 65kg. I do listen to the TR podcast, so I know this is not the optimal way to go for a higher watt/kg.

Welcome :v:t3:

Sounds what you’re doing is working for you, both FTP and weight loss wise. I have limited advice to offer but unless there’s a strong reason I’d continue doing that. The danger of changing your current success is that you mess up what is going well.

Imagine at your fTp and weight you’re a beast on the bike. Good work!


Personally, I’d stick with the 500kcal deficit and aim for that 0.5kg/week loss. You don’t have a hard deadline and slowly trimming down has a better chance of retaining power. Heck, I might even aim for a 300kcal daily deficit and take longer. You might not even notice you’re at a deficit.

What you have is working and appears to be sustainable. Stick with it and don’t mess it up by going too extreme.

Most people would kill for those power numbers and big power helps you on the flats and climbs. W/kg mostly helps on the climbs, so I’d prioritize retaining power over losing weight and potentially loosing power.


Thanks. I agree that changing something that seems tomwork and has given results seems like a bad idea. Will take this into consideration.


I would certainly not be shooting for deficits in the realm of 2000kcal, no matter what your method is. Deficits of >500 are generally considered unsustainable for sedentary people unless they have a significant amount to lose, and that’s not even considering the additional demands of training- even if you’re in z2, a 4 hour ride is still a decent amount of stress, and as the volume goes up eating enough between workouts becomes more critical. Depending on how low your total calories are, you may also be at risk for certain nutrient deficiencies.

As for ‘losing more weight by burning more fat’- your rate of weight loss is determined by total calories, so while some people might find z2 more achievable during weight loss periods, it’s not inherently more effective at producing it.

Ride you bike for fun, eat a moderate deficit., keep it simple. Not a lot to be gained crash dieting.


Yeah, doing a defecit of more than 500 is not recomended. For me 500 to 1000 has worked well so i will stick to that for the next period and when i get closer to the goal i will start to slowly drop this by somewere around 100 kcal each 3 day or so (this will be adjusted as needed to maintain weight).

But the thing i wonder is if zone 2 and 3 is basicly only burning fat, will teoretically doing 2000kcal extra z2 work and then eat 1000kcal after the workout (this is separat from the 500 daily deficit) will result in a faster, but still safe weightloss since the 1000kcal missing from this equation is burned from fat. I am no expert in this subject so i might be wrong on this. I just could not find any information on this today.

should you ditch a interval session for Z2 in order to burn fat?
TLDR: for weight loss, it doesn’t matter where the calories are coming from that you’re burning. your body re-shifts stores as needed.

the idea of “fat burning zone” as calorie burner is really to be questioned for endurance athletes, it’s largely relevant to sedentary people.

mostly sedentary people may have it hard to do any substantial activity that results in a significant calorie deficit. going Z2 makes it possible to cumulate some substantive calorie amount. a intensity/interval session reaching the same calorie burn could be better than Z2 (long-term performance improvement could be higher, muscle adaptation, after-burn etc). but sedentary people don’t just do 2x20 at sweet spot, for example.

for cyclists/endurance athletes, putting out 500-1000 kcal in a workout is not that hard. building your FTP over time with intensity/interval training/varied workouts has a major impact on your future calorie burn. just consider the difference between FTP 200 vs 250 for kcal/hour. you put out a lot more.

of course, if you’re already maxed on intensity, which I presume with SSB HV, adding a little endurance gives the option to maybe add a few hundred calories to your total deficit. but don’t ditch a quality session for z2 just because you want to burn fat.

Edit: you can show that you still burn carbohydrate in Z2 and not only fat by measuring exhaled CO2 vs oxygen consumption. It’s a different CO2:O2 ratio for fat vs carbs and thus you can calculate back what you’re using.

FIG. 1. Relative increase in energy derived from carbohydrate (CHO) utilization and decline in energy from oxidation of lipid (fat) utilization as function of relative power output. At crossover point, increments in relative exercise intensity result in increasingly greater dependence on CHO and less dependence on fat. Even though on absolute scale training results in rightward curve shifts, on relative basis training probably has minimal effects on curves relative to aerobic power. See text for explanation. SNS, sympathetic nervous system. (Brooks J Applied Physiol 1994)

A more current review is given in Purdom J Int Soc Sports Nutr 2018: Understanding the factors that effect maximal fat oxidation.



180cm and you’ve already lost nearly 10% of your body weight from 74 to 69kg.

It’s your business, obviously, but I would be concerned we are encouraging you to do something that will make you slower.


Thanks for the feedback and the input. A little correction. If I were to do this for experimental sake, I would not be skipping interval sessions for zone 2. I would replace the general build to do some weeks with zone 2 rides instead and then maybe start the general build later. But as some others have said I would probably be better off with doing the general build and then add on some extra z2 rides when I feel like it. This is what I am doing now. The last weeks of SSB 2 HV I have added 2-3 hours of zone two after some of the interval sessions in the weekend to bump up the TSS. Seems like this is working fine and body is handling it well so likely what I will be doing.

The idea of doing only z2 was to be able to do large rides all days of the week and to see if one theoretically could cycle at z2 indefinitely if one has fat stores ready and supplement with water and electrolytes.

Anyway, Thanks for all the responses on this subject.

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In the past when I’ve got back from a long ride and had a 2000 or so kJ deficit i’ve virtually emptied the fridge that afternoon resulting in no deficit whatsoever. In fact I’ve probably ended up with a surplus. What you are doing in aiming for a regular 500kJ daily deficit is obviously working, so carry on with it. I’ve started a similar plan a couple of weeks ago to see if I can shed some weight. One thing I’ve got to get over is that when I do a 2500kJ ride I can’t help feeling I’m “wasting” the opportunity to get a large calorie deficit on that day.

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Completely agree with this - I would definitely be focussing on increasing power or time to exhaustion rather than loosing additonal weight at this point. You clearly have a decent engine so fuel it and see where you can go rather than restrict it with limiting calories so heavily.


I wouldn’t try to do this. Even though in Z2 you’ll mainly use fat as fuel. You’ll still be burning those calories and energy your body needs. Just keep doing what you’re doing.

I’m kinda in the same boat and since the first week of july i went from 87KG and 272W FTP ( 3.2wkg) to now 78KG and 286FTP (3.65wkg) with -500 calories average daily. Middle of SP build and looking at my workouts i’ll go to 290+ after ramp test. What i did do is up my protein intake a bit, aiming for about 110g to 160g a day to keep the muscle build up.

So keep doing what you’re doing and you’ll decrease weight while gaining power.

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Feed the beast!

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My n=1 when I was going from 120kg to the 70kg ish, I aimed for 500 calories from diet, 500 from exercise, maintaining protein at target weight (which I can’t reference, but I definitely saw and researched that it was g per kg at target, not current).

However, I probably wouldn’t take that approach again, as FTP was static (albeit with w/kg benefits). If I went back in time, I’d tell myself to just stick to 500 calories from diet or even a percentage based. I feel I compromised my training, or at least my gains from training*.

*probably easier to say in hindsight though!