Weight Loss Facts

The Dieting Dilemma - Why Diets don't work

We are now in a paradox where there are countless diets promising weight loss, yet as a nation we seem to be gaining weight at a rate that by all accounts is likely to lead to a major public health disaster! What is going wrong? We have the Atkins Diet, the Zone Diet, the Liver Cleansing Diet, the Sugar Busters Diet, the Pritikin Diet, the Blood Type Diet, the list goes on and on, if these diets really work, why are 53% of New Zealanders overweight or obese. And why as a nation are we gaining weight at a gram a day!

The answer is likely to be multifactorial, but the key lies in sustainability. Many of us have successfully lost weight when we have embarked on the latest diet which promises the rich rewards of weight loss, but the problem is we don't maintain the weight loss. It is true that people have lost weight on low fat diets, low carbohydrate diets, low protein diets, high protein diets, high fat diets, raw fruit diets.... the problem is, after successfully losing the weight we slowly and sometimes subtly slip back into our previous eating patterns. The most common endpoint in dieting is weight regain. "Diets" are just not sustainable.

We are in an obesogenic environment. Food for most of us is readily available. We no longer have to go and hunt for our food or spend hours tending to our crops. As well as this, one of our primary problems is that we eat in the absence of hunger. We no longer eat to our appetite. We eat because we are bored, we eat because other people are eating, we eat because we feel down, and so on. In essence we have lost the ability to eat to internal cues only.

It seems we lose the ability to eat to our appetite early in life

Fascinating studies by Professor Birch of Pennsylvania State University have suggested that as youngsters we lose the ability to eat to our energy requirements. During infancy and early childhood, children show evidence of self-regulation of energy intake. Up to the age of about 3 years we tend not to be influenced by external cues and eating in the absence of hunger is uncommon. However Professor Birch has observed that children as young as 5 year olds who are given a lunch to make them full, will still eat more if treat foods such as chips, popcorn, ice-cream and biscuits are offered. This means that by age 5 years we have already begun to eat in the absence of hunger. Research also shows that this phenomenon is worse in children with parents who are more restrictive. The research showed that if mothers usually restrict foods, the children ate an extra 300kcal (1250KJ) compared to children with less restrictive parents who ate an extra 100kcal (418KJ). The children who ate the extra food tended to feel bad about themselves. This is somewhat reminiscent of what you see in adult dieters. Those who tend to be the most restrictive will subsequently binge, are more likely to feel bad about overeating, and are most likely to eat in the absence of hunger.

Fad Diets - Beware!

If a diet seems too good to be true, it probably is. This is an unfortunate fact surrounding fad diets. After all, if there was a diet out there that made everyone lose weight at a fast rate and enabled individuals to sustain the weight loss, no one would be overweight.

This means, Beware of fad diets.

Fad diets offer so much, but long term they just don't work.

Here's how to spot a Fad Diet. Look for the following points:

• Large and rapid weight loss
• Short-term diet - no exercise required
• Special garments or passive exercise machines involved
• Magical ingredients with special abilities to speed-up metabolism
• Claims that you can eat as many calories as you like and still lose weight
• Combinations of specific foods
• The use of only one or two types of food
• An exotic range of expensive and unusual foods
• Special powders and pills

If the diet claims any of the above it is likely to be a "fad" diet with no scientific backing for its claims.

There is much misinformation regarding dieting. In some cases, the methods used to reduce weight and/or the level of reduction achieved or desired, become dangerous. This can also negatively affect sports performance.

Rate of Weight Loss

The recommended rate of weight loss is 0.5-1kg per week. If you lose weight at a faster rate you are likely to be losing a significant amount of muscle mass or lean body mass. Remember that our lean body mass uses up a significant amount of calories. So if you lose muscle mass you need fewer calories, which of course is counter-productive.

We know that when we lose weight, on average about 75% of the loss is attributed to body fat, whereas 25% is attributed to loss of lean body mass. To lose 1kg of weight with this proportion of fat/lean requires an energy deficit of 4,200KJ (1000kcal) per day. This is a significant reduction of calories and so diets which claim a faster rate of weight loss are either untrue or you end up losing a lot of lean body mass.

The following equation explains how1kg of weight loss equates to an energy deficit of 4,200KJ

1kg weight loss is equal to 1000g

75% of weight loss will be due to loss of body fat = 750g

25% of weight loss will be due to loss of lean body mass = 250g (but of this loss of 250g, about 3/4 is water loss. Therefore about 62.5g of lean body mass is lost)

Now,

1g of fat is equal to 37KJ of energy, therefore 750g fat = 27750KJ

1g lean body mass is equal to 17KJ of energy, therefore 62.5g = 1063KJ

Therefore to lose 1kg of weight, you need a negative energy balance of 27750+1063KJ = 28813KJ over one week. Therefore per day you need a negative energy balance of about 4,100-4,200KJ.