Low fat diets, low fat recipe books and manufactured low fat foods are everywhere these days. Yet probably nothing in the area of nutrition, diets and weight loss has been so misunderstood as dietary fats.

The confusion is understandable. The ideas about fats that were accepted by the experts twenty or thirty years ago are now largely recognized to be seriously erroneous, yet it takes many years - maybe even a generation or two - before new scientific knowledge becomes common knowledge.

This confusion is readily exploited by various players in the manufactured and processed foods industry. "Low Fat" products are well labelled and easily found - but misunderstood by most consumers. Consumers expect that "low fat" somehow also means "low calorie". The manufacturers exploit that assumption mercilessly.

Always read food product labels. You will quickly discover that "low fat" almost always means increased refined flours and sugars. It does not at all mean "low calorie".

Processed foods aside, there are widespread misunderstandings about the word "fat", which can mean different things in different contexts.

Some "diet gurus" in times past have made such outlandish and just plain false claims that humans "can't get fat if they don't eat fat."

Recently I read a comment from a dietician (who should know better) supposedly debunking a diet 'myth' that bananas are fattening. She replied that this was wrong because bananas contain very little fat at all.

A food does not need to contain fat to be fattening. Those two different uses of the word "fat" in the same sentence have confused even that qualified dietician. Would she tell us that we can eat a bucket full of sugar because it contains no fat and therefore "isn't fattening"? I surely hope not.

To be "fattening" a food only needs to contain calories and be eaten above your energy requirements. It matters not whether those calories come from carbohydrates, fats or proteins as to whether a particular food is fattening.

Some fats actually stimulate metabolic function and can expedite weight loss. (Omega 3 and Conjugated Linoleic Acid are two examples published in major peer reviewed medical journals in recent times.)

Another piece of dietary theory from the 1960's and '70's, now clearly shown to be misguided, is that because fats contain nine calories per gram and carbohydrates contain four calories per gram, we will lose weight by replacing fats with carbohydrates. It sounds good, until examined closely.

That theory fails on several counts.

 1. First of all, proteins are also four calories per gram - the same as carbohydrates.
   Why then the recommendations to raise nutrient poor grain intake instead of nutrient
   rich protein intake with the same level of calories?

 2. Secondly, it is far easier to raise your carbohydrate intake than to reduce your fat intake.
   By following the advice to reduce fats and raise carbohydrates, you end up simply increasing
   your total caloric intake.

 3. Thirdly, this theory completely ignores nutrition. It concentrates on calories as if they are
   the only factor that is important in your diet. Fats are essential for many metabolic processes -
   not merely an energy source.

 4. Fourthly, if consuming processed goods for your carbohydrate source (breads, french fries,
   pastries, etc.), take a close look at the list of ingredients. Almost always, they are still loaded
   with fats or oils.

Another of the older beliefs now disproved is that "animal fats are bad but vegetable fats (oils) are good". Similarly, that "saturated fats are bad and unsaturated fats are good."

Modern research proves that there are good animal and other saturated fats, and there are bad animal and other saturated fats in terms of human nutrition and health. Likewise, there are both good and bad vegetable and other unsaturated fats (oils).

The falsehood that animal fats or saturated fats are always bad is very readily disproved. Human body fat itself is saturated fat. Even a healthy, normal weight person will be roughly 20% body fat. Without saturated body fat, you would die.

Another clear indication that saturated fats are essential to human health and nutrition is that human breast milk contains a high level of saturated fat. No-one questions the nutritional importance of breast milk - yet many contradict themselves by raising objection to all saturated fats.

Probably the most serious of the older beliefs now proven false is that low fat diets make you lose weight. While this can be demonstrated as true in the short term, it is now well known that it does not hold true longer term. Almost every study on this matter shows that people on low fat diets lose weight initially, then eventually regain even more weight than they had before they began the diet. The human body, if deprived of fats, will go into "starvation mode", slow the metabolic rate and encourage the conversion of glucose into fat and deposit it into adipose (fat) cells.

Low fat diets don't work for permanent weight loss.