There is a whole industry based on the desire to look good and for most people looking good means being slim. There are odd exceptions such as the woman who wants to increase her weight to 1000 lb to become [...]]]> "I’m going on a diet", is something I hear on a daily basis.

There is a whole industry based on the desire to look good and for most people looking good means being slim. There are odd exceptions such as the woman who wants to increase her weight to 1000 lb to become the world’s fattest woman.

Many of the people I know are serial dieters, they are searching for the holy grail of the diet world – something that will allow rapid weight loss without pain, without starvation and without lifestyle changes.

Some basics

Humans are omnivores. This means our digestive system is midway between herbivores (eat only vegetable matter) and carnivores (eat only meat). In theory we should be able to thrive on a mixed diet and adapt to just about any food.

We have evolved as a species to adapt to feast and famine. Our bodies become very efficient at saving energy when there is not much food around and as soon as food is plentiful we recover from starvation and lay down fat reserves ready for the next scarce time.

This works against most diets. To begin with you lose weight quickly then the body notices that its fat reserves are getting smaller and it switches to a slower metabolism to conserve energy. Dieters call this "the plateau". After a week or two on a plateau most diets tend to become boring and enthusiasm drops.

There are three basic food types: carbohydrates, protein and fat. You can alter your diet to change the ratio of these three food types.

Carbohydrates are described as simple or complex. They are broken down by enzymes in your body to form sugars. Simple carbohydrates break down quickly and give you instant energy but too much sugar in your blood is dangerous so your body mops up the excess by releasing insulin. Insulin grabs the sugar and converts it into glycogen. When it has enough glycogen it converts the excess into fat.

Complex carbohydrates take longer to break down but they too follow the same fate as simple carbohydrates, it just takes longer.

Think of carbohydrates as fuel that burns quickly and is dangerous in excess.

Protein is broken down by the body into simple molecules called aminoacids. Some of the aminoacids can be broken down into sugars but this is an inefficient process and it is only during starvation that this usually happens. Generally the amino acids are used to make new proteins that our bodies need to stay healthy. There are 22 different aminoacids and they occur in different ratios in food.

The main health issue if you eat too much protein for too long is elimination of waste, aminoacids that are not used for building new proteins are partly digested and the indigestible bit that is left has to be excreted via the kidneys.

Fat is absorbed by the body and used to make new compounds that are vital for healthy body cells. Specifically the fat molecules are used to make special cell walls that allow chemicals to move in and out of the cell at the right time. Fats are made up of chains of carbon atoms and vary in length. Fats can be saturated or unsaturated, the names refer to their shapes and their chemical characteristics.

The body doesn’t chop fats into little molecules very often, it tends to make do with whatever it gets so if you eat a diet with lots of short fats like coconut oil your cells will be different to those of someone who eats a lot of long fats, like suet.

The good news about fat is that you don’t have to eat much to feel really full up. Providing you don’t eat carbohydrate at the same time.

"OK the high carb diet isn’t working – let’s try the Atkins diet"

Types of diet

Starvation

This is also known as fasting. Some people believe that regular periods of supervised fasting with water and rest will cure many illnesses and lead to enhanced well being. This is not very interesting to the diet industry as there is not much profit to be made.

Calorie counting

Go to any supermarket freezer section or the chilled cabinet and you will find meals that claim to be "low calorie" or approved by one of the various companies who promote this style of dieting. While they adhere to the regulations, in my opinion this is an expensive and rarely successful strategy for long term weight control. I think that calorie counting is complicated, boring and takes no account of nutritional value.

Weird diets

If you eat a single item of food or a very restricted group of foods you are likely to loose weight. Your body will make extreme adjustments to its metabolism as it struggles to survive on an inadequate diet. In the long term you will either get bored or sick and as soon as you eat normally again you will rebound in weight as your body gathers reserves for the next famine.

The Food Combining Diet

This was very popular in the late 1980′s. The idea was that you kept your carbohydrate meals at least four hours apart from your protein meals. I don’t know anyone who still follows this regime and from what I remember it was difficult to follow and never very effective.

The F-Plan Diet

The F stands for fibre. The idea behind this diet was to increase the amount of fibre that you ate, being bulky fibre should make you feel quite full and you should end up eating fewer calories. Most people found that this diet increased the speed at which food passed through them causing what I shall tactfully call "upset tummy". Probably for this reason it fell out of favour.

"The F-Plan diet doesn’t seem to be very popular. He says it saves time if he doesn’t eat it"

Alli

Alli capsules are marketed as a "weight loss aid" and contain the drug orlistat which stops fat absorption. In terms of "upset tummy" this can almost go in the same category as F Plan because it works by making you so afraid of sudden diahorrea that you are frightened to eat anything containing fat. The idea is that by reducing fat intake you will eat fewer calories.

Clever diets

When the diet uses an understanding of metabolism there is a better chance of success but usually there is a lifestyle change involved.

Remember that food is made up from carbohydrate, protein and fat. Our bodies need protein and fat to repair themselves and maintain health, they provide the essential building blocks. Carbohydrates are just a source of fuel.

One of the problems with carbohydrate is the way it triggers insulin release. Insulin removes sugar from the circulation and then you feel tired and hungry. Time for another biscuit or another piece of cake. Too many insulin spikes are likely to stress the pancreas and if you are susceptible, increase your likelihood of diabetes.

Another problem is that simple carbohydrates act as appetite enhancers. How often have you been out for a meal, felt full after your main course, then eaten a sweet dessert and felt hungry again?

The Atkins diet

The Atkins diet cleverly bypasses this effect by keeping a high level of dietary fat. With so much fat in the bloodstream the body doesn’t feel threatened by starvation and the metabolic rate stays at its normal level. By cutting out carbohydrates the insulin spikes that link to hunger pangs are eliminated so you don’t feel hungry between meals.

It’s not always easy to avoid carbohydrate and eventually boredom sets in, however there are quite a few long term Atkins dieters who have successfully modified the regime into a comfortable lifestyle change.

The Dukan Diet

The initial phase of this diet excludes fat and carbohydrate, you only eat protein for 1 to 5 days, so the body has to get some energy by breaking down glycogen reserves and then mobilising stored fat. The body needs fat for cell repair and replacement among other things so will use body fat reserves.

The secondary part of this diet is the "protein" day. This is the lifestyle change that followers use to maintain weight loss. One day a week, for some reason they suggest Thursday, you eat only protein.

Carbs only

You will notice that there is no diet that relies on eating only carbohydrate. The reason for this is that such a diet will inevitably lead to obesity.

Diet Books