Resting Metabolic Rate and calorie deficit for weight loss

I recently had a DEXA scan and RMR test done at a lab. I’m 5’6" and weigh around 205 lbs. According to the results, I have a little over 25% body fat, my RMR is 1972 calories, and TDEE of 3057 calories. I don’t know how accurate the TDEE is. It says this is for someone that has a desk job but works out 3 to 5 times a week.

I’ve seen calculators online that recommend having a deficit of 500 calories to lose a pound or so a week. So I’m wondering if eating 2500 calories is eating too much if I’m trying to lose weight? Ideally I would like to be lose around 25 lbs of fat by August or preferably sooner. I’m also starting a build phase next week and concerned that being in a deficit isn’t the best idea. But I also feel like eating 3000 calories is going add weight. Is this supposed to be something simple and I’m overthinking it? Do y’all have any recommendations?

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500 kCal/day is really on the upper end of what is reasonable. I’d shoot for much less, perhaps 200 kCal/day. Losing fat is a long-term affair.


If i were in your situation, I’d try something different. Forget about calories. Try to find “tricks” to force yourself to eat less without measuring. For instance, eat two big meals a day only. Fast from 6-7pm til 11-12 next day. Don’t drink sugar in any form (including milk), don’t eat cheap calories. But allow yourself to eat all the rest and anything you want as long is high quality food.

And for biking I would do mostly LT1 for now. I can’t imagine the stress of wanting to fuel a demanding workout with sugar while trying to lose 10%+ of body weight.

Good luck


This is exactly the strategy I used to drop about 12 lbs that I picked up after a summer cross country ride. It eventually caught up with me and my training load. YMMV may vary, but I’m still on the last hole in my belt.

A good starting point for TDEE is 15 Cal per lb of bodyweight. That also means this goes down as you loose weight. With 205 lb, that puts you at 3075 cal, really close to what you mentioned.

This includes already some amount of exercise, I prefer to do the calculations without exercise and then add that in later depending on the workout. This because I have an office job and most of the additional calories burned come only from the workouts on the bike. As an estimate for the base rate we can do 13 Cal/lb, so that gives 2650 Cal for you.

To loose weight you could then aim for a 10-20% deficit relative to the 2650, which on the high end is the 500Cal that is mentioned often.

The strategy then becomes, eat 2100 Cal plus Cal from workout you did that day.

Now the most important part, these are all estimates and surrounded by a lot of uncertainty. Even intake is uncertain as food labels can be wrong and effective intake can differ. Therefore these numbers are starting points and need to be adjusted by feel. What you should feel is a small nagging feeling of hunger that moves to the background after a while and remains bearable. It should feel like you would still like to eat a little bit more.

Make small adjustments if needed. So if you have an unbearable feeling of hunger, add 200 Cal, preferably in the form of fruits and eat more veggies. If you feel totally satisfied most likely you need to cut down 100-200 Cal.


I can share what is currently working for me. I’m 49 & have battled weight since my 20’s when I was around 210 at 5’5". I’ve recently begun a weight loss phase with very little focus on training. I’m currently around 155lbs, I’m riding very casually 3 or so times a week & doing light strength work in the form of squats, lunges & pushups 3 times a week. I’m eating ~1350 calories a day between 10:00am - 6:00pm. Over the past month, I’ve definitely lost weight as I’m fitting into clothes I outgrew & have lost a full belt buckle hole. Honestly, right now, I think looking at the scale every day will add stress I don’t need so I plan to weigh myself only once per week. I’m going to keep going like this for another 2 months & think I’ll get to 145 or so. I will also add fasted endurance rides to my plate to once the weather turns more favorable up her in the northeast.

I also had success losing weight during a build/specialty phase in 2020 but it was mostly V02max & sprint type workouts because I ended up ditching threshold in favor of longer outdoor rides. I was running a 500 calorie deficit & did fine with it. It seemed like that type of work supercharged my metabolism for some reason & I easily got to 142 & I was setting PR’s on local segments that had stood for me for 5 years.

I honestly don’t feel like 500 calories is a huge deficit for anyone but you will need to “listen” carefully to your body to know if that is going to be too little fuel for you. I wouldn’t go more than 500, though. Good luck & let us know how this goes for you!


One thing to consider is that the quality of the food matters significantly. Calories on the package are generally produced using a simple process of heating the food in a sealed container until it is completely burned away. Your body doesn’t work like that. One, protein requires ADDITIONAL energy to separate the urea from the nitrogen so you can pee it out. That can equal as much as 30% of the calories you have eaten meaning 100 calories of protein may only actually be 70 calories stored. Two, fiber is not digested, but would be considered calories in the bomb calorimeter measurement I mentioned. It obviously differs between how much fiber a food has, but point being, not all calories from high fiber foods are absorbed by the body. Long story short, eating high protein and high fiber diets will lead to lower calorie absorption regardless of how the calories are counted on the package. This is one of the reasons these types of diets “work.” The side effect of choosing high protein, high fiber is also that you generally are faced with healthy food choices in order to achieve that, so it’s kind of a double win from that standpoint. You might see that even if you don’t lower your calorie consumption, but switch to high protein/high fiber foods, that you lose as much weight as a 500 calorie a day diet and that you are full because typically you can eat a lot more of these low-calorie dense foods.


Thank you everyone for all the information. The biggest change I think I need to make is to focus on the quality of the foods I’m taking in. I’ve always figured a calorie is calorie but that may explain why I never really make as much progress as I would like. I really enjoy cheesecakes, bread, and jasmine rice. I don’t think I can give those up entirely but I can definitely eat them less and eat significantly more vegetables. Gonna start with 500 calorie deficit and if I feel hungry, I will try to fill up on high quality foods.

I’ve been loosing weight for the last month or two. I decided to base my rate of weight loss on percentage of total weight. This is because I’m 6’6” and these hard rules like “no more than 2 lbs a week of weight loss” or whatever calories a day make no sense for a guy of my size. So I read quite a bit and found the optimum range is to loose .75%-1% of total body weight a week.

I decided to loose 2.25 lbs a week, or .8% of total weight per week, or 1125 calories a day. I have had a consistent daily deficit. I figure it out by totaling my current pounds lost, divided by days on plan, and then multiply that number by 3500. I do this every few days and it’s consistently at 1100-1150 calories deficit per day. I’ve lost 14.25 lbs over 44 days doing this.

I diet off the bike as much as I can. I try and eat on the bike at least 50% of my calories burned. Then the rest I make up in the kitchen. Off the bike I eat very clean, no sugar based product, hardly any dairy, no fast food or processed food other than protein bars and shakes. I eat several servings of fruit and spinach a day. I aim for about 1.75 grams of protein per KG of body weight, about 200 grams On the bike I try for cliff blocks and GU gels and allow one donut per long ride (above 40miles). I did a 65 miler and was very hungry and got pizza at 7-11. It was amazing!

My rmr is about 2800 and use my apple watch to track all the other calories and figure out how much of that is from my biking. It’s a bit of an art deciding what the Apple Watch data actually means. I take the net defecit from the bike ride and add it to the calorie deficit for the day. I also cut my meals down and save a lot for snacking after 6pm. It really helps, I just count it and make sure it’s the right macros.

Right when covid started prior to starting cycling I lost 60lbs or so with Keto. It was great, very delicious and no cravings. Now that I’m working on the other half of the weight I’m going slower and I think it’s more sustainable as a lifestyle change, the most important part.

Hope that helps.


I have had four DXA scans over the past year and a half. The first one, in April 2021, I was 215lb and 24.8% body fat, at a height of 192 cm (6’3½), 54.5 yrs old (at that time). Most recently, in July 2022, I did my fourth DXA and was 195lb and 15.9% body fat. Compared to the first DXA done 15 months earlier, I had lost 22lb of fat while gaining 3lb of lean mass. At the time of this most recent DXA, I also got my first RMR done. The RMR result was 1785 calories, vs an “expected” value (based on height, age, weight) of 1986 calories. This is the opposite of what we hear about exercising causing metabolism to speed up. My theory (just a theory!) is that my actual RMR is 200 calories lower than the expected value because I’m spending 12-15 hrs a week riding an indoor bike, and my metabolism is trying to be as chill as possible when not exercising.

My first phase of losing weight last year was simply a low carb diet combined with intermittent fasting, doing just a bit of strength training and no cardio. I was able to lose about 13-14 lbs this way. Then I started riding the bike at the end of last year and have really gotten into it. I am eating whatever I want but the DXA scans this year show I have continued to lose fat while gaining muscle. I will say that I find it much more enjoyable to focus on exercise than to focus on caloric restriction.

It’s great you’ve found something that works for you. I think the most important part is to find something you enjoy that works for you.

I’m curious how RMR is measured and how accurate it is. I believe calories in calories out, but of course accounting for the in and out can be highly imprecise. 100-200 calories is probably a rounding error when it comes to daily accounting.

The test I did used a BodyGem indirect calorimeter. They have you relax in an easy chair for a few minutes, then put a clip on your nose so you can only breathe through your mouth. Then you hold up this BodyGem device (about a third or half the size of a hair dryer) to your mouth and breathe through the mouthpiece for 5 or 10 minutes. I think it looks at the ratio of oxygen to carbon dioxide in your exhaled breath to estimate how many calories you’re burning. You can google indirect calorimetry for details. They claim an accuracy within 1-3% of the “gold standard” method, which presumably costs a lot more than the 50 bucks I paid for the BodyGem test.

In any case, I just did it for grins and wouldn’t try to base a weight loss plan off of it. I did think it was interesting that the measured level was more than 10 percent below the “expected” level, which would just be the average for somebody of my age, height, and weight. But since I am burning so many calories through exercise on a daily basis, I think it makes sense.

It’s really easy to get the internet or an app to tell you your predicted HRmax, or VO2max, or body fat percentage, or RMR. But unless you actually get these things measured in a lab (or the field, for HRmax), they are just averages and have as much chance of being correct as asking an app how tall you are or how much you weigh based on your age. They will just give you an average value.