Hypothyroidism or underactive thyroid affects a significant number of people, and is more common in females than males and in older people. It occurs when your thyroid gland doesn't make enough of the thyroid hormones thyroxine (T4) or triiodothyronin (T3), which slows down your body's metabolism, leading to symptoms such as tiredness and putting on weight.
Hyperthyroidism is an overactive thyroid – see here.
T3 and T4 control how quickly the body burns energy and how quickly reactions in the body happen. Metabolic rate affects lots of things, such as body weight, and how much you sleep. The hormones speed up the body's metabolism, causing processes in the body to happen faster. The production of the thyroid hormones is controlled by another hormone called thyroid stimulating hormone (TSH), secreted from the pituitary gland in the head.
Hypothyroidism usually develops gradually with mild symptoms at first, until there is a gradual slowing down of functions. Main symptoms are:
- Lethargy and wanting to sleep a lot
- Feeling the cold easily
- Dry and/or pale skin
- Coarse, thinning hair and brittle nails
- Sore muscles, slow movements and weakness
- Hoarse or croaky voice
- Change in facial expression
- Problems with memory and concentration
- Weight gain
- Fertility problems and increased risk of miscarriage
- Heavy, irregular or prolonged menstrual periods
- Slow heart rate
- Swelling of the thyroid gland in the neck - goitre
Hypothyroidism can be caused due to an insufficient intake of the trace element mineral iodine. This is one of the main causes of it in the World but rare in the Western World as iodine is abundant in our diet. Sources of iodine.
Autoimmune thyroiditis is the most common cause of hypothyroidism in the UK. This is an autoimmune disease caused by antibodies from the immune system attacking thyroid gland cells. Hashimoto's thyroiditis is the most common type of autoimmune hypothyroidism, where the thyroid gland swells up apparent as a goitre.
Hypothyroidism can be treated by drugs like T3, T4 or a thyroxine replacement, levothyroxine, in tablet form. However it can take many months to get the correct dose, so improvement in symptoms can be slow. In most cases treatment improves all symptoms. Once the correct dose of thyroxine replacement has been established, thyroid function should be monitored annually.
Dietary treatment is aimed around controlling weight and making the individual feel less tired. Most cases of hypothyroidism involve unwanted weight gain, but unfortunately weight can be really difficult to lose until the thyroxine replacement therapy is at the right dose. For this reason initial goals are to maintain weight and prevent further increase in body fat. Then when the doctors are happy with the drug dose, weight loss should be possible through a good diet and exercise regimen.
The following example meal plan has been designed for someone with hypothyroidism who wishes to control their weight sensibly. Obviously the amount of weight the person wishes to or has to lose will vary and depend on how overweight they are. The following is a good general guide, nutritionally balanced for weight loss to suit a sedentary adult.
Exercise will be a huge help in helping to speed up the rate of weight loss, although until drug treatment is under control, this may be hard due to lethargy. Light cardiovascular exercise (e.g. running, cycling, stepper, cross-trainer, treadmill, etc) for around 40 minutes at least three times per week. If possible do this unfuelled first thing in the morning, but if this isn't practical, later on in the day will also benefit both fitness and weight loss.
Like all plans, the one below is merely an example and portions sizes will need to be adapted to suit an individual's activity level, own lifestyle, daily routine and nutritional requirements. Use this to give you an idea of which healthy nutritious foods should be included, and don't forget to vary your food choices and to drink plenty of water through the day. The plan contains small but regular amounts of low glycaemic carbohydrate (see info here) foods which will help poor energy levels. See our Glycaemic Index Tables for GI values of foods.