So I read an interesting abstract from a study about BMR(basal metabolic rate) in women with PCOS. Have a look if you’re interested.
I’ve always known my BMR had to be lower than average, or I simply wouldn’t weigh as much as I do, or spend as much time exercising in order to lose weight, but I’d had no idea it could be that different. The numbers reported in the study are the ADJUSTED BMRs, so they’ve already accounted for activity level.
It does make sense. If you look at the difference they saw in women with PCOS + insulin resistance, and normal women, it’s a difference of 752 kcalories a DAY. That is huge. Even if you look at the PCOS women without IR, it’s still 278/day. That means, if you’re eating what the average woman should be eating to maintain her weight(1868 kcal a day, here), you’d be overeating by 1946 kcalories a week if you didn’t have IR and 5264 kcalories a week if you did. A pound of fat has about 3500 kcalories, so the non-IR PCOS woman would be gaining half a pound a week, and the IR+PCOS woman would be gaining 1.5 POUNDS a week. So, in a year, the PCOS woman without IR would have gained just shy of 29 pounds, and the PCOS woman with IR would have gained a staggering 78.2 pounds.
That makes many things from my past attempts to lose weight make a lot more sense. When I wasn’t trying to control my borderline insulin resistance, losing weight was a joke for me. I would cut my calories down to 1200-1400/day, and exercise on top of that, and I’d be lucky to lose maybe half a pound to a pound a month. Each week, I’d try and burn 2000-3000 kcalories through exercise, so let’s do some math.
Let’s look at the numbers for the PCOS+IR woman. It gives an adjusted BMR of 1116 +/- 106 kcalories. That means that, when adjusted for activity level, the women with PCOS and insulin resistance would need to eat between 1010 and 1222 kcalories a day to maintain their current weight. So, let’s assume, as I am borderline for insulin resistance, I fall somewhere between the bottom of the non-insulin resistance PCOS women and the top end of the PCOS+IR range. The bottom for the non-IR women is 1460, so halfway between is 1341 kcalories a day.
If I was eating 1300 kcalories a day, that would give me a calorie deficit of 41 calories a day. Since a pound of fat is 3500 calories, that means it would take me 81 days(just shy of two months) to lose a pound, if I wasn’t exercising. Let’s assume I was burning and average of 3000 calories a week through exercise, in addition to my dieting. That would give me a weekly calorie deficit of 3287, just under a pound of weight loss a week. Since I certainly wasn’t losing a pound a week, I assume my BMR actually fell in the IR+PCOS range.
If you’re at the bottom of the PCOS+IR range and eating 1300 calories a day while burning 3000 calories a week through extra exercise, you’d have a weekly calorie deficit of 970. That means you’d burn a pound in 3.6 weeks, which is much closer to what I was actually doing.
What is 3000 calories of exercise? It’s a heck of a lot. It’s running 30 miles a week. I was running between 20 and 30 miles each week, so let’s say I averaged 2500 calories burned each week. That would mean I would have had a net calorie deficit of 470 calories a week, and that it would take 7.2 weeks to lose a pound, which was pretty close to my reality.
Now that I’m taking metformin, things are a bit easier, but I’m still not losing weight as quickly as non-PCOS women do. I keep my calories at around 1300/day, and when I’m consistent with my exercise, I can lose a pound a week, sometimes even a pound and a half, which is huge for me. It also puts me some where between the low and median ranges for the woman with PCOS BMR.
I feel like this is hugely important information for a woman with PCOS, and it seems surprising to me that I’m just finding it out. Of course dieting doesn’t really work for me and I can gain weight without even trying. At least I’ll do okay if there’s ever a famine!