Why You Can’t Assume Every Overweight Person is Eating More

I wrote this as a comment on Liz at One Twenty Five’s post “My Candid Thoughts on Weight Loss” but it ended up being so long that I wanted to put it here as well! I’ve been meaning to address this subject for awhile anyway–it’s the same application of the logic behind my post “Why You Won’t Gain the Weight Back.”

Original Comment: “I’ve often thought the same about friends of mine who are unnaturally skinny despite all the ‘junk food’ we consume when we’re together.  Of course, some individuals have higher metabolisms than others, but the difference is minimal.  It’s not going to account for such a drastic difference in weight if the same amount of calories are consumed on a daily basis.  Conversely, I’ve had heavier friends who eat like birds when they’re out in public.  Makes you wonder how much they’re consuming behind closed doors.

My response: I agree with you, but also want to point out that the difference between what a thin person and a fat person can eat isn’t as great as you think. For example, a 5’4 125 lb 25 year old woman has a BMR of 1382 calories, while a 5’4 200 lb 25 year old woman has a BMR of 1708 calories.(Basal Metabolic Rate ie the number of calories your body would burn if you were in a coma). If they were both sedentary, the 125 lb woman would need ~1650 calories/day to maintain her weight, while the 200 lb woman would need ~2050. So that’s yes that’s a difference, but not THAT much–we’re talking an extra sandwich, not six Big Macs. 

Moreover, if the 125 lb woman was moderately active and went to the gym on a regular basis, she’d actually need about ~2150 calories/day to maintain her weight, so she could be eating MORE than the 200 lb woman and still be much thinner–actually up to 2600 if she was extremely active, and potentially even more than that if she had very low body fat/a percentage of lean muscle mass. This difference would be exemplified if the thinner woman was also taller–for example, a 5’10 150 lb woman would have the same BMI  (21.5) as the 5’4 125 woman but her BMR would be 1519 calories, so she would maintain her weight at ~1820 calories if sedentary, 2350 if moderately active, and up to 2890 if extremely active–again, potentially even more than that if her body fat was very low. 

Finally, someone who is overweight is far more likely to have messed up their metabolism through yo-yo dieting (it’s often a chicken-egg situation where the cycle of dieting causes someone to gain even MORE weight) then someone whose always been thin. So my hypothetical 5’4 200 lb sedentary woman might in fact need less than the expected 2050 calories to maintain her weight. Therefore, you could easily have a scenario where an overweight woman is literally eating 1000 calories a day LESS than her thinner friends and still not losing weight, even without accounting for initial/inherent metabolic differences.

Now none of this is meant to disprove your and Liz’s original point because I definitely agree there are a LOT of people who eat very differently in public than private. And some of this is just goes with the nature of public versus private situations–I mean, I’m obviously going to eat more at the Cheesecake Factory than I would eating dinner by myself in my apartment because I don’t have fresh bread, multiple course options, and delicious cheesecake in my apartment, you know? And it’s also true that if someone’s overweight, that means they were overeating at SOME point in their life, even if it’s not currently. But it’s definitely POSSIBLE for overweight people to eat a normal amount and certainly NOT of them are binging behind closed doors–because the difference between what a thin and fat person needs to sustain themselves isn’t as significant as most of us think, and is easily covered by differences in activity level.


One Response

  1. That definitely rings true for me, as the years have ticked on and my ED/yo yo dieting has modified my metabolism. It now takes significantly more work and less food to see the same results that I used to see at a younger age (and even factoring in age, it’s a difference). That said, once I reach a healthy weight I suspect I could maintain it now that I have the tools, though I’ve never successfully done it!

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