For many years, a low calorie/low fat diet was considered to be the best diet for healthy weight loss. But in recent years, low carb/high fat diets such as the Atkins Diet and high protein diets such as Charles Clark and Protein Power have swept the dieting world.
The new diets were initially rejected by the conventional medical world, claiming they would not work (or worked simply because they were low calorie diets in disguise). It was also claimed that the new diets were dangerous on account of high levels of protein and fat. The Atkins Diet came in for special criticism, particularly because of the ketosis which characterises the first stage of the diet. (Ketosis is the state where your body burns fat rather than carbohydrate for energy, and by-products of this called ketones are excreted in the urine, which enables dieters to easily test whether they are 'in ketosis'.)
However, more clinical studies have been done on the safety and efficacy of the new diets and the results have now forced entrenched opinions to change. The Atkins Diet in particular has been shown time and time again to be more effective than the conventional low calorie/low fat diet. The claim that ketosis is dangerous has been shown to be completely false. It arose from people who had not understood the science behind the Atkins Diet mistakenly believing that the 'benign dietary ketosis' of carbohydrate restriction is the same thing as the dangerous ketoacidosis of uncontrolled diabetes.
At the same time, many important clinical studies on the supposed link between high fat diets and heart disease have reported their results. The conclusions here have been a surprise to the conventional medical world, too. Views such as 'the only healthy diet is a low fat one' and 'a high fat diet causes high cholesterol which causes heart disease' are now scientifically unsupportable.
The issues surrounding fat in the diet and their effect on health are very complex and there is still much that is not understood. But enough is now known to validate the conclusions of diet trials investigating the effect of high fat diets such as Atkins on heart health. These look at indicators such as blood pressure and triglycerides (fats in the blood). Much to the surprise of the conventional medical world, these indicators often improve, not worsen, on an Atkins-type high fat diet.
Moreover, it has been found that those following a low fat so-called 'healthy eating' diet for many years actually had a worse risk of heart disease than those who had not followed it.
In terms of the efficacy of low carb and high protein diets, clinical trials have also found them to work better than the standard low calorie/low fat diet. The new diets have two main factors which distinguish them from low calorie/low fat diets. The first is that they recognise that there are important hormonal factors at play when you attempt to lose weight, the most significant being insulin. The Atkins and other low carb diets, and also the low GI and low GL diets which followed them, all control insulin as a major part of their premise.
By contrast, the standard low calorie/low fat diet ignores the insulin effect. High in carbohydrate foods (which are the ones which stimulate insulin), experts now believe the standard low calorie/low fat diet is entirely wrong for the sixty per cent of people who are estimated to overproduce insulin when they eat carbohydrates.
The second factor is the higher level of protein encouraged by the new diets. Intake of protein, because it often comes in high fat foods, is generally very restricted on low calorie/low fat diets. However, protein has been found to help dieters feel more full than carbohydrates. There is also evidence that eating protein has a 'metabolic advantage', in that you can eat more calories if the diet is high in protein than if it is low in protein and high in carbohydrate. In other words, the old belief that a calorie is the same for weight loss purposes whatever type of food it comes from is not true after all.
So in terms of which diets are best, the standard low calorie/low fat diet only works well for a minority of people. For the estimated sixty per cent of people who overproduce insulin when they eat carbohydrates, the best weight loss diets are the insulin control diets - low carb, high protein and possibly the diets which followed on from them, the low GI (glycemic index) and low GL (glycemic load) diets.
It is important to recognise however that many people have so low a tolerance for carbohydrates that a low GI diet will not work for them. In that case, a low GL or low carb diet such as the Atkins Diet is indicated.
The "Easy Guide to Low Carb, Low GI & Low GL Diets" explains more about the science behind these diets, which ones are likely to be best for individuals, how to choose between them and how to follow them.
However, even the best weight loss diets can fail. There are many other aspects of your health which need to be in balance before you can lose weight successfully. Repeated dieting (yo-yo dieting) and not eating enough can result in a diet plateau or stall where weight loss stops because you have become caught in the 'starvation mode', 'famine syndrome' and depressed metabolic rate traps. If your diet (of any type) is not working, these issues may be affecting you. You might also have food sensitivities, candida, nutritional deficiencies or thyroid problems. These can all result in you not loosing weight. More explanation of these problems and how to conquer them can be found in the book "Why Can't I Lose Weight".