On Monday, I had to go for a blood test. You see for quite a while now, I’ve been eating pretty healthily and doing 20-40 minutes of high intensity exercise most days, yet I’ve stayed the same weight. Since there’s a strong history of under-active thyroid in my family and since I have some symptoms (like sparce eyebrows, slower than average pulse, dry skin, brittle nails, tiredness etc.), I thought it would be a good idea to get it checked out. And since I have a health issue which requires me to have an annual full spectrum blood test to keep an eye on things, I went and got it done. And as usual, the thyroid hormone levels were within the normal range. They were on the low side of normal (a bit like getting a B minus on a school test), but normal nonetheless.

So I voiced my concerns to my GP. I told him about the weight and he said, “Well, at least you haven’t gained”. So I explained again, patiently, about my diet, my exercise, and the fact that my mother, my grandmother, and my father all have under-active thyroids and that my sister’s “normal” results were ignored for so long that she nearly died and it was only when the doctor sent her for further testing to shut her up that they discovered she had Hashimoto’s disease, and that while there might be nothing wrong, wouldn’t it be worth ruling it out? With that, he wrote me up for a full panel of thyroid hormone and thyroid antibody blood tests.

So there I was on Monday, sitting chatting to the nurse taking a phial of my finest and explaining why I was there. I told her about the diet and the exercise and out it came. The laziest brush-off in the history of medicine.

“Well of course, muscle weighs more than fat”

I felt sorry for her as I walked out of the room. She looked kind of shell-shocked because she wasn’t expecting my response. I said, “No! Muscle does not weigh more than fat, it just takes up less space. I’m a fitness coach and a sports nutritionist, so I do know how it works. A calorie deficit like the one I eat at should lose me about a pound a week. Right now, I should be well within my healthy weight range but I’m not. I’m maintaining at 2 stone over that. And even with the exercise I do, to have built that amount of muscle, I should look like a body builder. So please stop perpetuating this myth. If people hear that kind of nonsense from a healthcare professional, even one not necessarily specially trained in nutrition, they’re going to believe it, and it’s lazy junk.”

So, let’s explain, maybe a little less excitedly. Muscle and fat are different molecules with different structures, and in fact they both have three basic types but let’s not dwell too much on that. The molecules that make up muscle fibre are twisted in a rope-like structure, which makes them tight and dense. They’re then laid together, a bit like wires in an electrical cable. Fat molecules, on the other hand, are looser and frankly, have so many different permutations of structure that it’s a complicated business to even start. Suffice to say, the molecules are further apart and are joined in such a way as to give them more volume. And it’s the way they’re joined that determines the type of fat. And that’s it in a nutshell. Muscle takes up less space than fat. It’s as simple as that. So the next time someone tells you that muscle weighs more than fat, put them straight.

As it turns out, the results of my blood tests show thyroid hormones within normal limits, but thyroid antibodies over the top of normal. Obviously I’ll be waiting to see what the doctor says, but these are the same results my sister had. The fact that I’ve been eating healthily and exercising reguarly have kept me as healthy as I am. Food and exercise are the only ways we have to control our metabolism, and if that’s what it takes to put off the effects of whatever this is for longer, then that’s what I’m going to do.