Wednesday 12 January 2011

Scientific foundation of weight loss

This post is summarized from a variety of sources, including an excellent BBC program on weight loss and maintenance. There are too many false claims out there about weight loss, pseudo-scientific or not. This post is intended to provide some known facts about human biology which may offer some insights into controlling weight more efficiently. The bottom line is: there is no magic bullet/tablet/capsule/ingredient we can take to make all these extra adipose tissues disappear. Balanced diet and regular exercise are your best two bets in a long run for weight control. When it comes to weight loss or control, simple maths still stands. If you ingest more than you burn, you put on weight. Simple as that.

The human body is an intricately balanced machine. There are still many aspects we don't understand how human body works. Weight control is one of them. However, there are a few scientific findings revealed in the past two decades which may help us understand our body better and perhaps controlling weight with less pain.

Firstly, physiology 101 in why we feel hungry and why we feel full, in two simple bullet points.

1. What makes we hungry? Our body's hunger signal is called ghrelin, a hormone released by a gradually emptying stomach to signal our brain for food. An effective diet control plan has to control ghrelin efficiently, because if your brain is not detecting ghrelin, you will not have the desire to eat.

2. What makes us feel full/satiated? Two key hormones are important to tell our brain to stop eating. Hormone PYY, is released by GI (gastrointestinal) tract, mostly by ileum and colon after a protein-rich meal, and leptin, after a fat-rich one. Both are key to suppress our appetites and PYY is particularly good at it. Therefore, eating a protein-rich meal (while within a sensible number of calories) will help you feel full longer. Lean meat, fish, eggs and pulses are great way to enrich the protein portion of a meal.

3. Count your calories. Total calories consumed per day is still an important factor. It's the fundamental principle of weight control. If you consume more than you burn, bulges ensue. To lose weight, we must burn more than we consume. An average adult male needs 2200-2400 Calories per day and 1900-2000 Calories for adult female. For a more specific Calories calculation, Mayo Clinic has an easy calculator for that.

Now we know the biochemical basis of hunger trigger and control and the amount of calories we need per day. Here are a few things we could be the master of our own body, rather the slave of it.

4. Do not skip meals. You have heard it many times. Why? Think of ghrelin. Skipping meals leads to reduced stomach size which triggers ghrelin. Your brain is all red-up crying out for high-calorie food when you skip a meal. MRI brain scans are the proof.

5. Soup helps you feel full longer. Here is a neat trick to "fool" your brain. Experiments of the same meal blended into the soup form with water or in the solid form (taken with a glass of water) have shown that a meal in the soup form stays longer in the stomach, delaying the release of ghrelin (huger trigger). In contrast, when the same meal is consumed in the solid form with a glass of water, the stomach is emptied faster than when the meal is taken in the liquid/soup form because water just passes through the stomach almost instantly to the intestines. As a result, the stomach reduces its size more quickly with solid food, prompting the release of ghrelin crying for chocolate bars!

6. Dietary calcium helps the body excrete more fat. Ha, surprised? I was when I read about it. Two research groups, from Denmark and from USA, have independently demonstrated the positive correlation between dietary calcium and fat found in the excrement. How wonderful! If you are lactose intolerant, dark green vegetables tend to be calcium rich. If you are lucky enough to consume some dairy products without embarrassing effects, reasonable portions of cheese do make you healthy, you know!

7. Regular exercise, at whatever level, not only benefits your overall health, but also a great ally for weight control. Do you know that your body continues to burn calories hours after the exercise? You get free bonus calories burned without extra work. How marvellous!

8. Switch to smaller dinnerware size. When we are given more to eat, we eat more. By switching a 12-inch to 1 10-inch dinner plate, you can reduce up to 22% of the food intake.

I don't know about you but weight control has been a life long battle for me. I enjoy everything nice in life, including food. Part of me depends on good food to go on. However, I also realize that enjoying food does not mean eating without restraints. I am very lucky to be given this perfectly functioned machine and I actually like some exercise. I see it as my duty to work with what I am given and to maintain its state as long as I could. I hope my 8-bullet point list would help me remember some basic facts and principle guidelines in weight control. It's part of life.

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