To a hungry dieter, the promise of a low fat or fat free snack can be very tempting if it’s low in fat and low in calories, how bad can it be?

Low fat foods were championed in the 80s and 90s, when dietary fat was identified as a leading cause of heart disease. Food manufacturers quickly realised that ‘low fat’ sells, and fat became the dieter’s demon. However, fat plays an important role in defining a food’s flavour, taste and texture and contributes to satiety (a feeling of fullness). So to make low fat food more palatable, manufacturers added sugar, refined carbohydrates, sweeteners or even salt. And herein lies the problem.

When we eat something with sugar in it, or something that our body quickly converts to sugar, like refined carbohydrates, we produce a hormone called insulin that takes the sugar out of our bloodstream and in to our cells. But once the ‘sugar stores’ in our cells (particularly our liver) are full, the excess sugar gets converted to fatty acids which are then stored in our cells as fats. So even though sugar doesn’t contain any fat, our body can turn it in to fat.

As sugar is lower in calories than fat, and cheap, it has found its way in to all sorts of foods that wouldn’t traditionally contain sugar. Check the ingredients labels of foods in your house and you will be surprised how many savoury products are actually high in sugar. But beware - food companies often try to disguise sugar, labelling it fructose, glucose, dextrose, lactose, maltose, sucrose or syrup. Whatever type of sugar it is, it’s not good. Unfortunately artificial sweeteners aren’t good either as they can also make you put on weight.

So if sugar is the new dieter’s demon, what has become of fat? Well, the good news is that fat doesn’t necessarily make you fat. We need to divide fat into good fats and bad fats. Good fats are those found in nuts and seeds and their oils, olives, avocados and oily fish such as salmon, mackerel, anchovies, sardines, herrings and trout. Bad fats can either be saturated fats, like butter, cheese, milk, red meats and palm oil or trans fats such as those found in fried foods, biscuits, cakes and pastries, packaged snack foods and margarine. Each type of fat affects our body differently. Trans fats and saturated fats have been linked to heart disease, obesity, some cancers, liver dysfunction and diabetes. However, good fats are good for you: they can improve your health and even help you to lose weight.