Do 'Low - Fat' Foods Make You Fatter?
Whilst looking through a fitness magazine this month I came across an extremely interesting article which has provoked me to write this. I therefore cannot claim complete originality, but it brings to the fore so many interesting thoughts, by questioning the validity of eating ‘low-fat’, ‘non-fat’, ‘reduced fat’ type products when you try to lose weight!
The foundation of this was, not unreasonably, the fact that Americans were still getting fatter! This is despite the plethora of low fat, non-fat, reduced fat, low calorie alternative type foods becoming so readily available. It’s not that people are not selecting these alternatives because they are, so how can a food that has had some, if not all its fat (and therefore has fewer calories) removed, actually make it more fattening?
Let’s first look out how food is processed by the body (For reasons of simplicity we’ll just look at fat and carbohydrates)
Any carbohydrates when ingested (eaten) are, through the process of digestion, broken down into glucose molecules which enter the blood stream, ready for use as:
- glycogen storage
- fat storage
As diabetics are already fully aware, to remain healthy, the amount of glucose that is present in the blood stream at any given time (blood sugar level) needs to be regulated. A level too high leads to hyperglycaemia, a level too low, hypoglycaemia. For us fortunate enough not to have to rely on chemical means (non diabetics), this regulation of sugar levels is carried out entirely without our knowledge through the use of two hormones produced in the pancreas, namely insulin and glucagon. A level of blood sugar which is too high will result in insulin being released to ‘shunt it away’ therefore lowering this level. A level too low and glucagon is released which breaks down (catabolises) cells to give up their stored glycogen thus raising it. They work together in maintaining a ‘Balance’ (little plug there, hence capital B !). “But what does insulin do with this all this glucose?”. Great question because it is upon this action which the whole of the energy production v fat storage system works! I feel an analogy coming on !
Try to think of insulin as an employment exchange official and the glucose molecules as people who want work (energy production). As the people (glucose) turn up in the Employment Building (blood stream) they are met by this employment official (insulin). (Obviously he’ll only come out when there’s people in the building.)
When approached by someone who wants work, the official will either:
- If there is work available: Employ them (energy production)
- If there is no work available: Not employ them but put them on a short list (glycogen storage) for a quick source of energy should work suddenly increase (extra activity ie: exercise)
- If there is no work available: Not employ them and, once the short list becomes full, put them on file (fat storage) for work when the short list is unable to meet demand.
This process works very well as long as these two conditions are met:
- The unemployed arrive, and are processed, in a slow, steady stream
- There are enough officials to deal with the demand of processing.
In this analogy it becomes obvious that if 1/ everyone turns up at once or 2/ there are not enough officials EVEN IF THERE IS WORK AVAILABLE they cannot be dealt with in an orderly manner. The result being that since ‘putting them on file’ (storing them as fat) is the quickest and easiest option to our official then this is what he will tend to do. Remember since his primary responsibility to make sure the building doesn’t become overcrowded (maintain glucose level), energy requirements and ‘short lists’ are now of secondary concern !
So with this in mind let’s now go back to food digestion.
If we to avoid having all the glucose molecules ‘turning up for work’ all at once (because this will inevitably cause them to be stored as fat EVEN IF ENERGY DEMAND IS HIGH) we must make sure that they are processed in a slow steady manner. The obvious way of avoiding this is to spread our daily intake of food over several small meals, not over one or two meals larger meals.
However, there is another less apparent method.
Different foods can be turned into glucose (digested) at different rates. The speed at which they can achieve this is known as their Glycemic Index. If you eat glucose, it needs no digestion and is immediately available for energy. This is the baseline by which all other foods are measured .Glucose therefore has a GI (glycemic index) of 100. Baked beans however take much longer to break down and therefore take longer to bring about a rise in blood sugar. They have a correspondingly lower G.I of about 50. So what causes one type of food to bring about a rapid rise in blood sugar (high GI )and another not (low GI)?
Well, for a long time it was believed that due to their larger molecule size, complex carbohydrates were absorbed slower than simple ones, but recent research shows otherwise. It is now known that there are many other factors which cause a rise in glucose levels. These are - Fibre, other foods eaten at the same time, protein, fat, cooking and processing all have been shown to dramatically affect the speed at which a food is digested.
Back to our employment exchange analogy.
If everyone had to take off their coat (fat?) before they were able to queue, this would naturally slow down the speed at which the queue formed, thus making it easier for our official (insulin) to deal with them. But if everyone turned up without coats in the first place (fat-free?) a bottle neck and all its associated processing problems would occur. So the incorporation of coats (fat) helps keep the queue flowing nicely hence the numbers ‘on file’ (stored fat) will be kept to a minimum! Interesting eh ?
Work demand (calorific requirements) remains constant, so too many people (glucose) with or without coats (fat free or otherwise ) will still be stored on file (as fat).
Obviously I’m not advocating everyone to go out and eat lots of fat, though I still believe it should make up about 20% - 30 % of the daily calorific intake, providing saturated fats are kept to a minimum.
I hope that this article will provoke many of you to think twice about jumping blindly on the ‘low-fat’, ‘fat free’ diet bandwagon. By all means continue trimming fat from meat before cooking, grilling rather than frying etc. but if it takes a high degree of processing in order to turn a food into its ‘low fat’ alternative (white flour and margarines especially!) it could well end up becoming more fattening (though lower in calories!) than its natural alternative.
N.B. The milling and grinding of coarse stone - ground grain to produce fine white flower, (and therefore the reduction of particle size and the resultant speeding up of the rate of absorption), began in the 17th century, about the same time that the incidence of diabetes (the need for more employment officials or insulin) and obesity (inability of the employment exchange to cope)