27 year old male - 5ft 11in

7 Months ago i had a BMI of 40+ (21.5 stone).

After sticking to a 1000-1500 daily calorie intake (Counting & weighing everything) i have dropped to a BMI of 33.6 (17.4 stone).

I saw my GP before doing all this and he said that my BMI was that high i really didn't need to worry about burning muscle / under-eating (Within reason of course) as the shear excess of fat would just burn of first.

Now the BMI is down to 33.6 from 40+ i just want to update my understanding of safe / recommended deficits.

Is there a recognized calorie deficit vs BMI ratio that i can use to determine a target calorie deficit as my BMI carries on going down?

A graph with BMI on the X axis and recommended calorie deficit on Y axis would be perfect.

  • 3
    Congrats on your progress so far. @info is correct that although your BMI is showing improvement, it is not the best measurement to base your progress upon. Your body fat percentage will give you better information as to whether the weight you are losing is coming from fat or from muscle loss. If your body fat percentage improves then you are on the right track. If your body fat percentage does not improve or increases, then you are likely not getting sufficient nutrients to maintain or increase your muscle mass. Commented Feb 13, 2013 at 2:13
  • Also, you may be interested in BMR. Here are a couple of links, but someone else may have a better link: fitness.stackexchange.com/questions/6808/…, and fitness.stackexchange.com/questions/6366/…. Hope that helps. Commented Feb 13, 2013 at 2:20

1 Answer 1


BMI isn't something you use to calculate your personal fitness, it is a statistical measurement and highly inaccurate for personal use.

There are a lot of diets that 'speed diet' your weight down and don't care about muscle loss, what counts is the result on your scale to make them look efficient.

Safe rates of weight loss are mostly determined by your fat storage, the more fat you have the more Calories you can safely burn from them. A guideline is provided in this study and according to that study the maximum energy transfer rate from your body fat is about (290±25) kJ/kg d, that means: ~79kcal per kg (of fat) per day.

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