Any malfunction of the thyroid glands, which help regulate metabolism, can cause weight gain if either of two hormones produced by these glands - thyroxine or T3 (triiodothyronine) - is insufficient. This is termed hypothyroidism. (Another disfunction, hyperthyroidism produces too much hormone and weight may be lost.)
This can come about in a variety of ways; if mild it may be corrected by increasing your intake of iodine which is vital in the production of the thyroid hormones. If more severe you may need artificial thyroid drugs.
If you think you have a thyroid problem (other symptoms may be cold hands and feet, feeling sluggish and lacking in energy, constipation, dry skin for example) you should talk to your doctor who can arrange a blood test. If this is the problem and it is corrected, surplus weight should gradually go as your metabolic rate is restored to normal.
Problems with the adrenal glands may possibly also contribute to weight problems - some specialists say that with a permanently stressed life these glands, which produce the stress hormones epinephrine(adrenalin) and norepinephrine (noradrenalin), and cortisol, get 'exhausted' and this can set off a chain of events which may produce weight gain. Again, you need to see your doctor if you have long term stress and have gained weight disproportionately to the amount you eat.
By the way, interestingly, some foods seem to suppress the action of the thyroid - these are particularly soya and soya products, and also members of the brassica family including cabbage, cauliflower, spinach and brussels sprouts.
Lastly, it is estimated that of all cases of obesity, only a maximum of 3% are caused by underactive thyroid, so don't be too surprised if this isn't your problem.
What does 'the energy equation' mean?
The energy equation, or energy balance equation, is a way of expressing how your body balances its intake of energy (calories) with its expenditure of energy (calories).
The equation is thus:
Change in stored energy = energy intake - (minus) energy expenditure.
All this means is that:
If energy intake equals energy expenditure then there will be no change in stored energy (bodyweight).
If energy intake exceeds energy expenditure, then there will be an increase in stored energy (bodyweight gain). This is called a positive energy balance.
If energy expenditure exceeds energy intake, then there will be a decrease in stored energy (bodyweight loss). This is called a negative energy balance.
Theoretically, weight gain or loss can be measured like this:
3,500 calories ingested in excess of energy expenditure means a llb weight gain.
3,500 calories burnt in energy expenditure in excess of energy intake means a llb weight loss.
As the body converts all surplus food (be it fat, carbohydrate or protein) to body fat, for stored energy read fat. However, paradoxically, when weight is lost by creating a negative energy balance some of the weight lost is lean tissue (e.g. muscle).
Water losses and gains are not taken account of in the energy equation as water is not stored energy (it is calorie-free).
In practice, 3,500 calories burnt or eaten do not always equal llb of weight lost or gained, because of other metabolic factors in humans. However, it is a reasonable blueprint and one upon which all weight-changing regimes rely.
Is it possible to put on weight without eating more?
Yes it certainly is. A positive energy balance (see previous question) can be achieved not just by increasing your energy input (eating more) but also by decreasing your energy output (doing less physicial activity). Anyone who has been an active sportsperson and then gives up and puts
on weight knows only too well the truth of this. As an example, if you give up one hour a day of, say, walking to and from work, but continue to eat in the same way, you would be expending about 200 calories a day less, which would equal 1,400 calories expenditure less a week - which would mean a weight gain of 1lb in 2 weeks! And they say exercise doesn't help you lose weight!
Although reduced physical activity is the main cause of weight gain other than overeating, other variables may be at play too. For example, as you get older metabolism slows down slightly, all other factors being equal, so that would cause a slow weight gain. Illness, depression, drugs and other factors may be involved in unexplained weight gain too. If you feel you're gaining weight without a good reason, talk to your doctor.
Why do I never lose weight even though I hardly eat a thing?
There could be several reasons for your lack of success. Firstly, you may already be at a reasonable bodyweight - people come in all shapes and sizes, largely governed by genetic make-up and there is a wide range of weights within which you are still 'average'. If your genetics say you are, let's say, your natural weight at 10 stone, then you will find it hard to slim down to 8 stone because you wish to look like Kate Moss. Maybe you are already thin - and then of course getting even thinner will be harder. So rule one - aim for a reasonable weight.
If you really are overweight - but not obese - it could be that your metabolic rate is low because you don't take enough exercise and have a small proportion of lean tissue (muscle) which is more metabolically active than fat - as we age these problems may become more acute. Your metabolic rate may be genetically slower than average, for which there are dozens of reasons being discovered by the obesity scientists and this is another reason to aim for a reasonable, not low, weight. In additon, the WHO says that menopause reduces the metabolic rate slightly.
If none of these seem to be your problem it may be that you are taking in more calories than you think you are. All the studies that I can find which have tested slimmers under controlled scientific conditions, measuring actual calorie intake against their previous reported intake, have shown that intake is under-estimated on average by between 12 and 25%. For example, one study published in 2000 by the International Journal of Obesity showed that the actual intake of the participants averaged 1,888 calories but their reportage averaged 1,576 calories - a difference of 16.5%. The worst ' guessers' underestimated their intake by over 50%!
Another experiment in controlled conditions using people who had claimed that they couldn't lose weight, showed steady weight loss with each of them on a diet of 1,000 calories a day. This is now considered too low a calorie level for sensible slimming today, but the point remains the same.
People tend to underestimate portion sizes, forget to count calories in drinks, foods nibbled while preparing meals, and so on. Try weighing and measuring your food intake and keeping a food diary for a week or two and see if this could be the case with you.
What causes a big appetite and can it be controlled?
Appetite - or hunger - is a basic survival mechanism controlled in the body by the hypothalamus, which ensures that we take in sustenance and thus stay alive. Many experts believe that a big appetite is a natural reminder of the not too distant past (in anthropological terms) when food was not easy to come by. When we did find it, we ate all we could as insurance against starvation - surplus stored as body fat would normally be used up for energy before the next meal became available.
These days, of course, food is so plentiful for us in the Western world that we never get a chance to use our stored body fat. But the appetite mechanism hasn't quite caught up with that yet.
That is one explanation. Other factors are also involved. One famous research study on rodents showed that they ate much more when given a choice of a variety of foods that when given a restricted choice - the 'cafeteria effect'. No doubt many of us do the same - a good example is the revival of 'appetite' after a savoury meal, when the pudding appears - suddenly we're 'hungry' again! Anything new or novel also has a similar effect in stimulating the appetite. The food manufacturers know this and exploit the 'new' and '50 varieties' themes to make us buy more
in the supermarkets.
You may also experience increased appetite when eating your special favourite foods. Habitual eating - eating a certain thing as a certain time - is also often mistaken for true appetite.
High levels of physical activity seem to increase the appetite in lean people- which is necessary to restore the energy balance - but it appears that in obese people who exercise, this is not usually the case.
In women, appetite increases naturally via hormonal messages during latter pregnancy and in the pre-menstrual phase. Seasonal affective disorder (SAD) may also increase the appetite for carbohydrates which help production of the 'happy' neurotransmitter, serotonin.
In fact scientists are just begining to unravel the chemicals, proteins and hormones in our bodies which can effect appetite and therefore weight. For over 10 years they have known about the hormone leptin, a product of the ob obesity gene. In rodents, lack of leptin increases appetite but in humans, leptin deficiency is rare - so giving extra leptin to obese people will rarely work. Indeed, obese people normally have high levels of leptin as they have more adispose tissue than
slim people, and the hormone is stored in body fat. However it may be that obese people are resistant to leptin (as many are resistant to insulin) and this mayeffect appetite and result in weight gain. More research needs to be done.
Meanwhile there is interesting research on the body chemical dopamine which, along with the other neurotransmitters including serotonin and norepinephrine (noradrenaline) helps to regulate appetite and is linked with the 'pleasure factor' we find in food. Available dopamine seems to be reduced in people who are obese and who are compulsive eaters.
Maybe in the future there will be drugs based on leptin and/or dopamine to help beat overeating. Meanwhile, scientists have found that exercise helps increase the body's sensitivity to both substances.
So what can be done about a big appetite which is making you overeat? Plenty. Research shows that eating slowly can help to moderate the appetite because the brain takes about 10 minutes to register full feelings - research that is backed up by a recent study showing that fast eating is linked with fat-bellied people!
Eating more frequently can also help to control the appetite by regulating your blood sugar levels and it is best if small, frequent meals contain foods low on the Glycaemic Index, such as pulses, wholegrains, and most fruits and vegetables. Appetite may also be blunted a little by drinking a large glass of water a few minutes before the meal.
Appetite can be controlled by certain drugs currently available on prescription. Ma huang is a 'natural' alternative to one of these drugs, sibitramine, and is sold in over-the-counter supplements with guarana. At least three other appetite-controlling factors have been discovered - e.g the nueropeptide GLP - 1, the hormone orexin and the compound C75, but research on these is still at an early stage.
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