Good news for weight watchers - science conquers appetite

© HiPaCC Ltd 2005

Linda Cusmano We undoubtedly evolved from ancestors who foraged and hunted for survival, a far cry from the modern world of fast food and supermarkets. However our digestive system, teeth and closest relatives leave us in no doubt that we have evolved to eat and digest a wide range of foods, from meat to nuts and vegetables. This flexibility has been the essence of our survival and evolution over a hundred thousand years of climate change.

Now we suspect that the process of evolution is much faster than we first believed. Sudden alterations in our environment, such as disease, climate change or famine may have dramatic effects upon which genes are successfully passed on to the next generation. Within the eighty or so generations since early man first began farming, our digestive systems have adapted to a diet which contains much larger amounts of complex carbohydrates and dietary fibre. The ability to store calories during lean times was vital to our early survival, and women who could not store fat over the winter were less likely to raise and feed healthy offspring. Before the modern era of food surpluses created by the introduction of new industrial farming methods, most people were lean, and starvation was common even in George Orwell’s time. Indeed only a Century ago being fat was a sign of affluence and fertility in Victorian Britain, and a “full” figure was regarded as a status symbol. These famine genes which favour the storage of surplus calories, once our key to survival have now become our problem, as we all strive to stay slim, healthy and sexually attractive.
For almost three generations now we have lived in times of excess. The United States and European Union subsidise agriculture to the tune of tens of billions of dollars a year, cheap processed food is abundant, and “fast food” chains return a profit on meal items that cost less than a dollar. The recent epidemics of diabetes and obesity are the price that we are paying for such abundance. Genes which evolved to survive famine, which may have arisen during the Ice Age, have now become the genes of adversity as heart disease and diabetes exact a heavy toll. Sexual preferences have changed accordingly, and even a modest roll of fat around the waist is considered by most to be a deterrent to romantic activity. Yet we are under constant pressure from friends, family and the media to eat, drink and to make merry. Traditions of generous hospitality, in combination with foods that have been engineered by food companies to encourage food cravings and to prevent satiety, make our attempts to stay thin a constant battle.
As is traditional, the media seeks to attribute blame to someone or something which is perceived to lie at the root of the problem. In recent years the villain of the peace has been carbohydrates, and consequently low carbohydrate diets such as Atkins, ZONE and CSIRO have become all the rage. However, carbohydrates, far from merely being the “gasoline” that powers our brain cells and muscles, are also pivotal in determining whether our entire system perceives that it is in ‘starvation’ mode or in a state of satiety. Carbohydrates regulate both our mood and our sense of contentment, and all systems, from our endocrine glands to our metabolism are synchronised around blood glucose levels. For these reasons a sustained low or zero carbohydrate diet is far from ideal, even though a diet rich in carbohydrates may lead to obesity or even diabetes. Clearly a more balanced approach is required.
For a diet to be successful in achieving weight loss it should possess five key elements. First and foremost, the intake of calories must be appreciably fewer than the number that are expended; second, it must fit in with the way we live today; third, a diet should be balanced, varied and healthful; fourth, it should be accompanied by at least a modest exercise program to encourage fat metabolism within muscle; and fifth, and perhaps most importantly, it must control appetite. Diets which rely on will power and abstinence alone are almost certain to be unsuccessful, as appetite is an irresistible natural force that is driven by the body’s nutritional needs and hormonal balance. An understanding of the biological causes of appetite will allow us to manage or suppress it naturally, or perhaps even to design a drug to block it completely, ultimately making the diet itself a subconscious activity.
For many, a successful weight loss program is a siege against appetite, which is the body’s natural response to a shortfall in calories or nutrients. For example appetite may be stimulated by a deficiency of iron, B-vitamins, blood glucose or amino acids, which we will in turn perceive as a food craving for chocolate, bread, fruit or an egg. There are a number of natural hormonal systems within the body which signal whether the body has entered a state of satiety, or ‘sensation of satisfaction’. These include the release of insulin from the pancreas and leptin from fat cells which act at the level of the hypothalamus, not withstanding the newly discovered gut hormones PYY and obestatin. Unsurprisingly, many cases of obesity arise from a breakdown in the functioning of these hormonal systems, suggesting that many individuals are the victims of obesity rather than the cause. As with all checks and balances in the body, there are also hormones which act to stimulate appetite including insulin’s opposite number glucagon and the gastric hormone ghrelin.
Until a new generation of appetite-suppressing drugs have cleared customs, there are a number of useful techniques that we can employ to keep appetite at bay. For example, drinking green tea, which contains the potent anti-oxidant catechin (which in addition to its famed cancer-preventing properties, is also a natural appetite suppressant) is an effective weapon in weight loss. Drinking plenty of water also prevents misplaced thirst becoming a craving for sugary or milky drinks.
As your mother may have told you (and she was right), eating small snacks between meals can ruin your appetite. Whilst this may have been a bad thing in her eyes, for those of us trying to stay slim and sexy this may come across as being bad advice. Snacks consisting of fruit or multi-grain cereal bars which are rich in dietary fibre add volume to a snack or meal. Fibre reduces caloric density, filling the stomach, thereby suppressing appetite. High fibre carbohydrate sources such as wheat germ, processed bran or ‘whole meal’ flour also have a lower glycemic index, slowing the rate at which carbohydrates are digested and glucose is absorbed into the bloodstream. This is good news for suppressing appetite and also for preventing the sugar highs that may ultimately trigger insulin insensitivity and diabetes.
This is a useful strategy for inducing satiety, but the latest finding, and one of the founding principals of the HiPaCC diet, is that protein-rich meals naturally suppress the appetite. This one finding explains why so many Atkins dieters consumed fewer calories, even though their diet was high in fat. In contrast foods which are high in both fats and carbohydrates tend to increase both appetite and caloric consumption, as anyone who has had a donut or a burger addiction will tell you.
People on a high-protein diet tend to express more contentment with their food than those on a low fat or low carbohydrate diet, explaining why the F-plan diet struggled to maintain popularity. It is now commonly accepted that people express distaste for those diets which contain little or no protein. Perhaps more surprisingly dieters are also averse to those which are deficient in at least one essential amino acid, revealing how finely tuned appetite is to the body’s nutritional needs. These observations become clearer when we understand that dietary proteins generate a number of hormonal signals which regulate both appetite and digestion.
This brings us to the recent CSIRO Total Well-being Diet, which is high in protein, low in fat, and encourages moderate levels of low glycemic index (GI) carbohydrate foods, a diet which seems to have been inspired by the Australian barbeque. Whilst it may prove tricky to balance this simple combination, it should be noted that cycling levels of dietary protein intake is important for a number of reasons. Many specialists believe that sustained high levels of protein consumption may place undue strain upon kidney function, especially in diets where carbohydrates are restricted, and the long-term health implications of high protein diets maintained for lengthy periods remain to be evaluated. This may be especially true when lower levels of high GI foods are advocated such as in the CSIRO diet, as high protein diets with reduced carbohydrate intakes may eventually lead to ketosis. In fact there are many strong arguments as to why a ketogenic (low carbohydrate) diet may be less than optimal for good health. Indeed experts do not recommend ‘sustained calorie-restricted high-protein diets’ because they restrict the intake of ‘healthful’ foods which provide essential and balanced nutrients, and may also compromise vitamin and mineral intake, aside from potential cardiac, renal, bone, and liver complications. It is for these reasons that the new HiPaCC diet advocates cycling between high and low protein intakes during the week. Perhaps most importantly the human body, like nature, is cyclical. Initially someone on a new diet, exercise regime or work program will have success with their new system, but after a short time the body adapts to the changes and becomes resistant to further gains. Constant change and cycling are necessary within a diet to prevent such adaptation from preventing further weight loss.
Appetite is the body’s natural signal in response to a nutritional or calorific need. Like all motivational drives in the body, including sex and sleep, appetite is a complex interplay of hormones and biochemical cues which are integrated within the hypothalamus in the ancient mid-brain. It is a powerful and undeniable motivation which underlies genuine need. The aim of the HiPaCC diet is to suppress and harness the appetite naturally, and of course there’s no need to eat everything on your plate if you’re not hungry...