Now it is understandable why people may think this, because after all they share the same name, but the truth is the fat in your diet is probably not the reason you are overweight. Take the Inuits (Eskimos) for example, their diet consists of around 90% fat, 10% protein and any small amount of fruit or veg they may be able to lay their hands on. They are not an obese population; obesity and heart disease are practically unheard of. The Masai tribe has a similar high fat diet with no obesity, never mind an epidemic!
Now I'm not saying everybody should head out and feast on whale blubber but it simply highlights the fact that eating fat, even in large quantities does not make you overweight, nor is it the main cause of heart disease (but we'll leave that discussion for another time).
There is no metabolic pathway for converting dietary fat into body fat, we are only able to store excess glucose (sugar) as fat. Meaning it's a lot more likely to be excess sugar or carbohydrates in your diet that has caused you to gain weight.
*Sugar is a type of carbohydrate*
Fat is an essential part of our diet for various reasons:
§ Certain Vitamins (A,D,E & K) are fat soluble, so can only be absorbed with fat
§ Essential Fatty Acids cannot be produced in the body, so need to come from our food
§ Proper functioning of the nerves and brain
§ Maintaining healthy skin, hair and nails
Fat is also a good source of energy that adds flavour to our foods and low-fat diets have long been associated with depression.
As we can see, our bodies have lots of uses for fat whereas there is only one use for carbohydrates, which is energy. If we eat more fat than is needed for the functions listed above there is still the potential to convert those extra calories and use them for energy, but if we overeat carbohydrates the only option we have is to store the excess as fat. That is why it is more likely an excess intake of carbohydrates that is the reason for weight gain or the reason you are not losing weight.
All this being said, I'm not advising people to tuck into pastries, pasties and the like. The fat in your diet should come from natural sources, so meat, fish, eggs, full fat dairy products, fruit and veg (coconuts and avocados are a good source of fat as well as oils such as olive and rapeseed).
Just a quick note: The reason we compare carbohydrates with fat, rather than protein is because carbohydrates are generally what are added to peoples diet when they cut down on fat. High protein diets are widely accepted as being very damaging to health due to a build up of ammonia in the blood stream and the added strain on the liver and kidneys.
In the near future I will write an article exploring fat in more detail, including the different types of fat, their benefits and GP's favourite topic cholesterol