Under experimental conditions, PYY enables obese people to resist the temptation to eat excessively. It is currently being pursued as a potential treatment for obesity. Other gut hormones affecting appetite and the sense of satiety are also known. One of them is called is GLP-1. Like GIP and PYY, it is made and released from the intestine in response to certain foods; like GIP, it is involved with the disposition of the individual constituents of the food within the body, mainly – though not exclusively – through their ability to stimulate the release of insulin. It, or something very like it, is already available commercially for the treatment of Type 2 diabetes. Ghrelin and obestatin, both discovered within the past ten years or so, are produced in the stomach and affect appetite in opposite directions: ghrelin stimulates appetite; obestatin inhibits it.
Just how important the newly discovered hormones are in deciding whether or not you become obese is still uncertain. It’s one thing to discover how a hormone works under research conditions, quite another to apply it in a clinical situation.
We are still a long way from understanding how these new hormones work in human beings under everyday living conditions. Studies on the changes produced in grossly obese patients whose only salvation comes from by bariatric surgery – operations on the stomach that are currently the only effective method of treating this life-threatening condition – will undoubtedly advance our knowledge. So will experiments and clinical trials using pure hormones as they become available, exactly as happened with insulin and diabetes.
While the availability of a plentiful supply of food is a prerequisite for the development of obesity, the relationship is far from being a simple one. Most people with access to alcohol do not become alcoholics; a few, especially those with a genetic predisposition, do. The same is true for food, but whereas it is possible to abstain from alcohol completely – and so achieve a cure of the ill – this option is not available to the obese. Obese patients may find it comparatively simple to stick to a very low-calorie, synthetic, liquid, formula diet and lose weight at just about the maximum theoretical rate – about half a pound or a quarter of a kilo a day – but as soon as they are permitted to replace one of the meals with solid food of their own choosing they stop losing weight and may even gain it.
The idea currently being propagated by single-issue pressure groups is that obesity is due to one particular type of food constituent, whether it be fat, sugar, rapidly absorbed starches or combinations of them – in particular when they are provided in the form of foods such as hamburgers, pizzas, chips, crisps and other energy nibbles. This would be laughable if it were not so misleading. Obesity is a genuine, recognisable medical problem. It will not be resolved by simplistic dogma that is based on unproven opinion rather than on evidence.
The fact that an increase in the incidence of obesity coincided with a rise in the availability of fast or convenience foods is not evidence of their role in its causation. Exactly the same argument could be advanced for the rise in the use of telephones, or – better – central heating. Human beings burn off many more calories to stay alive in a cold environment than when they are warm. It would nevertheless be as foolish to assume that the answer to obesity is to return to the days of cold and damp housing as it is to suggest that banning the sale of energy-dense fast foods, or labelling them as bad for you, will the solve the problem. Decades of dietary advice for the prevention and treatment of obesity based on avoiding first this and then that type of food have all resulted in failure.
Any new way of losing weight is likely to produce an effect lasting a year or two, especially if aided by pharmaceutical appetite suppressants. A small percentage of dieters do manage to sustain their weight loss, but this is achieved not merely by changes in their diet but by altering their whole way of life. Indeed, the few long-term, large-scale interventional studies that have succeeded in reducing the incidence of obesity, and more especially Type 2 diabetes, have relied upon intensive re-education and alterations in lifestyle to incorporate changes in exercise as well as in eating habits. The importance of moderate and regular exercise in achieving weight loss cannot be overemphasised – not because of the calories consumed in doing it but for its general effect upon the metabolism of the body.
Other factors are important also. The way food is eaten, whether as regular meals or ‘on the hoof’, the time of eating, the size of individual portions and what they consist of, as well as the genetic and hormonal factors in the person eating the food, all have a part to play. The old adage that it is better to leave the dining table wanting more than to leave it fully satiated is probably still as good advice as any for those genuinely wanting to avoid obesity.
This may be difficult to achieve in an ‘I want it now’ society, but it might be helped by teaching elementary nutrition and the long-term health risks of obesity at an early age rather than resorting to propaganda based on half-truths and unproven ideas. But for many of the morbidly obese, the ones really at risk, it is only advances in the understanding of the pathology of obesity and its specific and appropriate treatment that offer any genuine hope of sustained benefit.
BY STANLEY FELDMAN
THE MYTH: Junk food causes ill health.
THE FACT: There is no such thing as food that is bad and food that is good for you.
The term ‘junk food’ is an oxymoron. Either something is a food, in which case it is not junk, or it has no nutritional value, in which case it cannot be called a food. It cannot be both. Ask most people what they understand by the term and they think of McDonalds’ hamburgers. None of their explanations for why hamburgers are junk food makes any sense; rather, they believe hamburgers are the cause of serious health problems because they have been told it is so. Any food eaten to excess is, as Paracelsus said in 1538, potentially harmful. Morgan Spurlock ate a diet composed solely of McDonalds’ food for a month for his film Super Size Me. At the end of that time, he felt unwell and had put on weight. Had he eaten a similar weight of ‘healthy’ sardines for the same time he would no doubt have felt just as unwell and put on just as much weight! No particular individual component of any mixed diet is harmful. The concept of ‘good foods’ and ‘junk foods’ is nonsense.
Some rather ill-informed individuals have so convinced themselves of the dangers of hamburgers that they have suggested taxing them or giving them a red warning label. Quite why hamburgers should be considered such a threat to our health that they should be singled out for taxation defies reason. Why should mincing a piece of beef turn it from being a ‘good food’ into one that is such dangerous ‘junk’ that it needs to be taxed in order to dissuade people from eating it? What would happen if, instead of mincing the meat, it was chopped into chunks and made into boeuf bourguignon – should it be taxed at only 50 per cent? To try to justify this illogical proposal, these self-appointed food experts tell us that hamburgers contain more fat than a fillet steak. They fail to point out that the ratio of protein to fat in a hamburger is usually higher than in most lamb chops, and that most hamburgers contain less fat than a Sainsbury’s Waldorf salad.
But, that aside, why should the fat be bad? Would these same people like to tax the cheese offered at the end of the meal because, after all, it contains the same basic animal fat as the hamburger? Or perhaps it is the hamburger bun that they feel is unhealthy. But the same self-appointed dietary experts would not object to a helping of food in the form of pasta or a slice or two of wholemeal brown bread (which, by the way, is the bread with the highest level of pesticide). The pasta, the bread and the bun produce a similar carbohydrate load in our food and are absorbed into the bloodstream as the same constituents. As for the tomato ketchup on the hamburger, it is rich in vitamin C and the antioxidant polyphenols that are supposed to keep cell degeneration and cancer at bay.
There is no such thing as junk food. All food is composed of carbohydrate, fat and protein. An intake of a certain amount of each is essential for a healthy life. In addition, a supply of certain minerals,