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Why we get Fat

The ABC Health Report had a very interesting segment on studies done on why we get fat.

Dr Norman Swan interviewed Dariush Mozaffarian an Associate Professor from Boston who is also an Epidemiologist at Harvard School of Health. Below are some notes from the episode.

Studies looked at the main determinants of very slow weight gain - examining lifestyle changes simultaneously.

Every person gains about half a kilo a year which is not noticeable but does allow you to become overweight.

Life style factors for long term weight gain

They looked at three separate long term studies i.e. 10,000 people over a year with up to 20 years of follow up.

The  Findings
Not all food and beverages are treated equally this goes against conventional wisdom like everything in moderation, total calories and adjust the fat content in food.

It found there are very big differences in how foods relate to weight gain.
Some foods when increased did not lead to weight gain. (loss actually)

Loser Foods

Fruit nuts whole foods - when you use these foods you displace other foods in the diet and lose weight.
Nuts associated with relative weight loss

Neutral Foods

Low fat diary, whole fat milk and cheese (surprisingly).

Weight Gain

Foods associated with weight gain include the obvious ones like white bread and refined foods.

Cutting fat out of your diet to get weight loss was not substantiated by the science

Weight Positive Foods

Important was the quality of the carbohydrate you eat - starches refined grains.
Any kind of refined carbohydrate and complex sugars lead to weight gain.
Potatoes (no matter how prepared), all types of refined grains (breakfast cereals, white bread, white rice)


Meats processed and unprocessed. (no explanation more study required)

When you eat a refined food white bread or potato it has almost the same metabolic effect on your body as eating table sugar.
We breakdown those long chains of carbohydrate which are sugar almost immediately. (burst of sugar - same as eating sugar).

Carbohydrate quality

For a balanced diet we must look at overall carbohydrate quality.
Hi GI turn into sugar quickly and in turn lead to more food being eaten and feeling hungrier quicker.

A study showed with children if they have a high GI breakfast they will eat more for lunch.
Hence what you eat at one meal also effects what you eat at the next meal.

Important to concentrate on foods with good carbohydrate quality.
Pasta has low GI compared to potatoes and white rice and if cooked al-dente it is even lower and if mixed with vegetables (lower GI).

Fat type did not matter Saturated, Polyunsaturated or Monounsaturated.
This does not mean that other health effects of these fats did not matter just weight gain is not influenced by preference.

Physical activity (up and down), television watching and sleep deprivation linked to weight gain

The study found the overall effect of diet was 2 to 3 times the effect of physical activity.

Sleep is associated with weight gain, low sleep (less than 6 hours) decrease sleep, increase hunger - caused by our change of preferences to comfort foods when losing sleep.

refer How to lose weight while you sleep

Television watching

Major impact is through the diet not lack of physical activity (2 major studies confirmed this)
There was reduced weight with less TV however this was due to kids snacking less (advertising - subconscious effect).
If TV was replaced with reading they still lost weight.

Hence it is easy to gain weight (half kilo per year) however a few minor changes can keep that down.

Avoid processed refined foods. Fruits vegetables whole grains nuts and yogurt are best for losing weight long term.