Metabolism — the process by which your body converts food into energy — can be affected by number of the things you do every day, both positively and negatively. Your individual metabolism is also dependent on a number of innate factors, including your age, sex, and size.
Two other factors affect your metabolism. One is the amount of energy it takes for your body to process your food each day, which stays relatively consistent. The second, as you probably guessed, is the amount of physical activity you engage in every day. As one study notes, “even trivial physical activities increase metabolic rate substantially,” so exercise of any kind is the largest factor in determining your metabolism.
That said, some people have a high basal metabolic rate (BMR), which means they burn more calories while at rest than those with a low BMR. It’s not fair, but it’s true.
There are also a number of reasons why your metabolic rate is what it should be. For instance, the function of your thyroid gland is to convert the iodine from your diet into thyroid hormones T3 and T4, which then regulate your metabolism. Thyroid function has significant control over the rest of your bodily, including your weight, cholesterol levels, and the rate at which your body processes food.
An overactive thyroid (hyperthyroidism) can increase your anxiety, make it difficult to gain weight, and make you moodier. An underactive thyroid (hypothyroidism) can affect your ability to sleep, make it difficult to lose weight, and lead to joint and muscle pain.
We asked a few doctors and dieticians to guide us through the ways in which, through diets and regular habits, we might be getting in the way of our own metabolism and thyroid function.
If you do have a thyroid disorder, gluten — found in foods containing wheat, barley, rye, or spelt — can indirectly affect you by “irritating the small intestine and disrupting absorption of hormone medications,” says Jennifer Cohen Katz, a culinary nutritionist and registered dietician.
Although iodine is necessary for the production of thyroid hormones, it’s possible to overdo it.
“Adequate iodine intake in essential to thyroid health,” according to Katz, but “getting too much is a danger.” Foods that are rich in iodine, like kelp, sushi wrapped in seaweed, seaweed salad, iodized salt, and iodine supplements, can disrupt thyroid function. ”Excess iodine may cause flare-ups in individuals with thyroid disorders because it stimulates autoimmune antibodies.”