Caloric Deficit how much ?

Hi @Susan_RD_101 ,
i am on a weight loss journey since long time. I lost so far about 36kg.
Today I am still working on the "last few" kg that are missing to get me to the "normal" BMI range.
I am on a WFPB Diet locked myself to 2000 cal per day (to have the cronometer "2 lbs per week goal). I make sure that I hit all the vitamins and micronutrients targets.
The weight loss is about 1 kg per month (feels very slow for me)
My BMR is 1837. My total energy consumption seems to be about 2900-3000 per day in average with the consumption that the Fitbit Watch reports back to cronometer.
In cronometer the 6-Month average is still about 3000 total calorie consumption.
I do weight training 2x per week and go running 2x per week for 1h. Especially on those running days my total energy consumption is as high as 3800 per day. On those days I get really tired towards the end of the day.

My question is, is my cal target per day too low ? Am I overstressing my body ?
Should I increase my cal on those 3800 days ? But on the other hand the weight loss seems to be "very" slow - maybe the Fitbit is overestimating my activity.
But by a deficit of 1000 cal per day I should get 2kg per month.
Are there any scientific papers to read where they investigated optimum calorie deficit levels for weight loss ? Especially that I am so active ?
I heard of this "slowing down the metabolism" myth when eating low calorie over a long time. But 2000 shouldn't be low.


  • @mk75

    Thanks for your question! You brought up a lot of really good discussion points, which I'll do my best to address.

    First, since you have already lost a significant amount of weight, it makes sense that your continued weight loss efforts will be much slower. Keep in mind that the body dislikes losing weight and lowers the metabolism as a way to compensate. At this stage, I would probably aim for ~1/2 lb per week; rapid weight loss may not be as sustainable as slower weight loss.

    I also wonder if you're possibly double-counting calories as your calorie burn seems quite high given the volume you are doing. If you are using a smart watch to track your calories, I would make sure that you set your Cronometer activity level to sedentary. You may need an extra snack on the days you are more active (if you're hungry) but your calories don't really change day-to-day.

    I wouldn't eat less than your BMR, as this could result if further reductions to your metabolism.

    And lastly, keep in mind that the BMI categories aren't the best indicator of a person's ideal weight. I never feel the need to fight to get someone within a BMI category; instead I prefer to look at outcomes like fitness, bloodwork, etc.

    Susan Macfarlane, MScA, RD
    Registered Dietitian Nutritionist
    As always, any and all postings here are covered by our T&Cs:

  • edited September 2019

    Hello @Susan_RD_101 , thanks for your comments.
    with "aim for ~1/2 lb per week" do you mean adjust the goal target to "~1/2 lb per week" or just accept a "~1/2 lb per week" with the current calorie goal of 2000 ?
    Regarding the double-counting, yes I made sure that I have set Cronometer to none activity level. Even if the fitbit is overestimating the activity by 20% I should be in a huge caloric deficit.
    My bloodwork was recently fine, awesome lipid levels. I am now on probation period without the last blood pressure pill I had been taking. I love WFPB, that was really the missing piece in my life to get me on the right track.

  • @mk75

    Regarding your first question, I would adjust your Cronometer settings so that your goal is 1/2 lb of weight loss per week. That said, I would keep aiming for ~2000 kcal per day, appreciating that your body will lose weight at its own pace.

    Kind regards,

    Susan Macfarlane, MScA, RD
    Registered Dietitian Nutritionist
    As always, any and all postings here are covered by our T&Cs:

  • Thought I would hijack your post since I also have a question about calorie deficit. My BMR is 1465 and at 183lbs I have lots of weight to lose so I set it to 2lbs a week. This gives me a daily calorie allowance of less than 500 per day. I wear a Garmin but the calories earned from that is either approx 250 (for a 30 min run) or if I'm just at home wandering around (housework, general walking to hang laundry, etc) it's only registering about 20kcal for my activity for the day. Am I doing something wrong or does it expect me to be living off 500kcal a day in order to lose weight?

  • edited May 21


    2 lbs/wk is a pretty aggressive goal. I had that absolute weight lost rate for a month or two with calorie intake close to BMR and activity level in the semi-active to moderate range, but at starting at nearly twice your current weight! But I was noticing a reduction in weight lost rate over time. After COVID-19 changes to my work schedule reduced my cycle commuting in about half, the reduced weight loss rate started to get discouraging. About 3 weeks ago, I upped my activity level considerably - cycling about 1.5 to 2 hours nearly every day (~370 miles so far in May, regular cycle commute is about 22 minutes/4.3 miles each way, so this is more than twice my pre-COVID-19 cycling level) - and I'm back to losing 2+ lbs/week (eating about 110% BMR and still weigh about 1.5 times your current weight). However, this is pushing at the activity level I can do without eating more. I really don't think 2 lbs/wk is a reasonable goal for someone your size unless you have a very high activity level.

    FYI: 1lb of fat is about 3500 calories, so burning 1lb of fat in one week takes about a 500 calorie/day deficit.

  • @Lebatsirk

    It sounds like you've subtracted 1000 calories from your BMR to get this target. What we want to do instead is calculate how many calories it takes to keep you at your current weight (which includes your BMR plus activities of daily living plus exercise calories) THEN subtract 1000 calories.

    At 183 lbs, I'd calculate your energy expenditure as a sedentary adult to be around 1750 calories. With exercise, this would be closer to 1900 calories. At minimum, you should be eating at least 900 calories per day.

    Now, the challenge with this is that 900 calories is very unsustainable and can be difficult to maintain. My advice is to choose a calorie deficit that doesn't leave you feeling hungry and gives you enough energy to exercise. For many people, this tends to be between 250 (1/2 lb) to 500 (1 lb) calorie deficit per day.

    The other thing to keep in mind with weight loss is that over time, metabolic adaptation occurs which will slow the amount of weight you will lose (so the closer you get to your goal, the further it seems). This doesn't mean you can't lose weight but don't give up if you're seeing the scale slow down!

    Happy to answer any other questions you have on this topic!

    Kind regards,

    Susan Macfarlane, MScA, RD
    Registered Dietitian Nutritionist
    As always, any and all postings here are covered by our T&Cs:

  • I didn't do any subtractions myself. Cron calculated my BMR to be 1451 based on my information (obtained from GP measured height, digital scales, and fat percentage from scales) so I'm not sure why you think it should be over 1700. My activity level is set to none because I wear a Garmin, which tracks my daily activity and any formal exercise. Hovering over the budget image tells me that I need a deficit of 998 to lose 2lb a week, hence the low calorie allocation. My daily activity is low at the moment because I'm studying, so I'm only earning <20kcal a day for that, and if I do 30 mins of actual exercise that's around 250kcal burned to add onto my daily allowance which still doesn't give me a lot more. I've figured out something that works better for me now anyway though, so the calorie allowance isn't a worry any more, but thank you for the replies and advice 🙂. In case it helps, Cron is currently showing that I've consumed 637 kcal, have burned 1723 (1451 BMR and 271 for today's exercise) and that I have 88kcal remaining. I think I've interpreted the way it works correctly.

  • Cronometer's BMR formula does not take into account body fat %. There are BMR formulas that use lean body weight (obtainable from weight and body fat), but the one Cronomenter implements uses age and weight (possibly also gender).

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