Dr John Wright

Gastroenterologist
MbChB MRCP(UK) PhD

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The DNA diet

Dr John P Wright
Updated: Nov 2017

Maintaining an ideal body weight

Since man became sentient on eating THAT apple in THAT garden, body shape has been central to man’s self-image. It may be one of the few things that separates us from our fellow primates. In spite of this near obsession a brief walk through your favourite shopping mall is enough to show that we are failing miserably in our pursuit of the body beautiful.

Why do we struggle so? Surely one look at the mirror should be enough to convince us that we have lost the plot? This universal obesity is not just a blob on the landscape but a serious health hazard. Most people would agree that we need to lose weight and look after our bodies better.

Traditionally the observation that there is no obesity in a concentration camp has suggested that we just need to eat less. This trite advice has not worked. The variety of diets, tricks and fads to lose weight is depressing. We all know fat people who eat too much but we also know thin people who eat too much. We also know fat people who eats less than we do. Finally, why do most overweight people stabilize and not continue to gain weight indefinitely. We need to admit that the relationship between body shape and diet is not understood. If we throw fitness and exercise into the mix, things become really complicated.

We need to better understand our desire for food, our use of food to fuel exercise and our basic metabolic rate which uses food to keep us alive and warm. When we were young, sudden weight gain from a weekend of overeating would rapidly reverse during the following week. What has happened to us when any weight gain quickly becomes a permanent feature?

The first fundamental step in self-understanding of the human species has been the human genome project which in February 2001 published its results to that date. A 90 percent complete sequence of all three billion base pairs in the human genome. For the first time ever, our blueprints are available for scrutiny. Everything about us is written in our genes. The shape of your head, the strength of your arms and possibly your body shape are all subject to the master plan.

Unlike blueprints which define physical shape, our genes define the processes that create our shape. This critical difference complicates our understanding inordinately but offers a multifactorial approach to body shape control.

At present the role of each gene is deduced from looking at the characteristics of people who have that gene. This approach is fraught with danger and misinterpretation. An association may be interesting but maybe incidental. If serious depression is associated with increased alcohol intake does that mean that alcohol is the cause of depression and we need to search the homes of depressed people to find the hidden alcohol store? Clearly while the relationship between depression and alcohol remains complicated it is reasonable to advise the depressed to avoid alcohol.

To fully understand the role of each gene on bodily processes we need at least a biochemical hypothesis and a full elucidation of the chemistry involved. Pending this data, the observations being made around the effects of different genes on metabolic processes is useful in providing a clue to the relationships between diet and body fat.

With this back ground a DNA analysis of genes related to fat and carbohydrate metabolism, glucose / insulin balance and fat deposition offers a new approach to body shape control.

Currently about 20 genes are analysed in a “Dietary DNA Profile”. Associations related to these genes may give some insight on saturated and unsaturated fat balance, carbohydrate / insulin response, exercise / energy utilization and appetite patterns. In addition, certain lifestyle factors such as effects of circadian rhythms may also be deduced.

The use of DNA analysis to advise on dietary manipulations for the individual is a work in progress. The interactions of genes and environment is incredibly complicated. So far remarkable results have been reported. The large number of start-up companies around the world offering DNA analysis and advice may suggest that, like the blood group diet, this is a passing fad, but the evidence is accumulating that DNA analysis offers a broad-based view of human energy utilization and storage.

In conclusion it is difficult to overestimate the long-term effects of the human genome project on all aspects of human health. On balance it seems to be worthwhile to have a DNA analysis done to better understand your metabolic processes that control your body shape. It certainly makes more sense than a trip to a concentration camp.