30/07/2013 13:37 BST | Updated 29/09/2013 06:12 BST

Junk Food as Addictive as Heroin and Tobacco


As a weight management practitioner of twenty years and a nutrition researcher I have become increasingly concerned about the volume of 'junk food' in the modern diet. I believe this is driving a wave of feeding addictions. Far too many of my clients tell me that they feel weak, experiencing a complete loss of control around highly palatable fatty and sugary foods. Many say the relationship with these products is totally controlling their lives and that they feel disempowered and unable to break free. Buying it is a compulsion, even though they know that it will lead to an inevitable gorging, followed by self-loathing and despair. This sounds remarkably like an addiction to me.

So what is junk food? Well, there is no internationally agreed descriptor, though I suspect most people would recognise the highly processed, fatty, salted, and sugar laden, nutritionally void products to which I refer (low micronutrient, high macronutrient). The processing removes much of the 'live' aspects of the food such as the polyunsaturated oils where the essential omega fats are. The aim is to preserve the product, as healthy polyunsaturated oils when exposed to the air turn rancid. When considering our diet we would do well to remember the old nutrition expression "good food goes bad"!

Many of the edible products of today are so far removed from the real thing that they simply act to confound digestion and override our natural satiety mechanisms. Obesity is just one of the more obvious chronic lifestyle conditions that result from eating products that we were never designed to eat. One of the enduring problems is that junk foods displace real foods, leading to lasting changes in our palates. Rats fed on junk food will refuse normal rat chow when junk food is withdrawn, fasting for many days despite plentiful chow.

Vitamins are also destroyed in the high temperature and aggressive industrial food processing techniques frequently used today. Minerals are removed with the extraction of fibre to enhance taste and 'mouthfeel'. The glycaemic index (how fast carbohydrate is absorbed into the blood stream) is also dramatically increased in such processes. This leads to high blood sugar resulting in high insulin which sends blood sugar crashing, causing production of a hormone called glucagon to signal the liver to release glucose to restore blood sugar. Insulin and glucagon are powerful hormones and all of the above leads to fatigue and exhaustion for the consumer.

There is a striking feature about natural food that is often overlooked: sugars and fats simply don't appear in abundance together in the natural world. Fats are plentiful in nuts and seeds and in animals and fish. Consuming fats results in a powerful dopamine response as the brain rewards us for eating an energy dense nutrient. Sugars on the other hand are largely confined to fruits and come in the form of fructose. The purpose of fructose is to tell us that the fruit is ready to eat. As sunlight penetrates the capsule, the long chain carbohydrates shorten to form sweet fructose. Rather than being bitter or sour, the fruit is now sweet and its consumption provides a serotonin based feedback reward from our brain to encourage further feasting. Therefore in the natural world these two separate brain reward circuitries would not be simultaneously activated, and more importantly the volumes of sugar (fructose) and fat involved would be modest.

A typical chocolate bar is 50% sugar and 35% fat, and this highly concentrated synthetic combination sends the brain into a frenzy of hedonic pleasure. Triggering a flood of dopamine and serotonin in the brain. Over time, continued consumption of junk food leads to a progressively deteriorating chemical balance in reward brain circuitries for rats. As dopamine diminishes, the rats quickly develop compulsive overeating habits, consuming larger quantities of junk foods until they become obese. The animals completely lose control over their eating behaviour; the primary hallmark of addiction.

Exposure to such 'dysfunctional foods' not only encourages overeating but also displace more healthy snacks such as fruit and vegetables, lowering the quality of the diet. A lack of antioxidants that protect us from free radical damage, alongside the harmful effect of excess belly fat, puts the consumer at risk of the damaging metabolic and cardiovascular diseases such as diabetes, high blood pressure and cholesterol and general damaging inflammation. I believe that children fed a junk diet are particularly at risk of becoming addicted and subsequently succumbing to these conditions which will develop into life threatening diseases later in their lives.

Finally you may be interested to learn that I don't believe that a person can become addicted to food, however, this stuff is not food!

This blog was written by Alan Jackson MSc. To find out more about health, fitness and nutrition as taught in personal trainer courses go to