Eating Right – The typical Singapore breakfast is nasi lemak, fried bee hoon, white bread, roti prata, porridge. For lunch at the hawker center or food court, it is chicken rice, nasi bryani, prawn noodles. Similarly for dinner.
This is a recipe for putting on weight around the tummy and love handles. Here’s why.
Foods, particularly carbohydrates are rated on their Glycemic Index (GI). The GI is based on their effect on blood sugar levels in the first two hours. It compares carbohydrates gram for gram across individual foods. Another index, the Insulin Index (II) is based on the effect of food on the insulin (from the pancreas) level in the body.
Carbohydrates that break down rapidly during digestion have the highest glycemic indices.These include white rice, white bread, biscuits etc. Carbohydrates that break down slowly, releasing glucose gradually into the blood stream have a low glycemic index. These include wholemeal bread, bran, oatmeal porridge. A low GI food will release glucose slowly and steadily. A high GI food will provide a rapid rise in blood sugar levels which may be suitable for energy recovery after endurance exercise or for a diabetic person experiencing hypoglycemia.
In a study [1] of about 38 foods, it was found that glycemic and insulin scores were highly correlated. There are some instances, however, where a food has a low glycemic value but a high insulin index value. This applies to dairy foods and to some highly palatable energy-dense "indulgence foods." Some foods (such as meat, fish, and eggs) that contain no carbohydrate, just protein and fat (and essentially have a GI value of zero), still stimulate significant rises in blood insulin.
When food is digested and absorbed into the blood as blood sugar, the pancreas releases insulin. Insulin binds to receptors in the cells to facilitate passage of the nutrients carried by the blood into the cells. In the case of muscle cells, to be used as energy. In the case of fat cells, to be stored as fat for a rainy day.
Ordinarily fat cells are highly receptive to insulin, much more so than muscle cells. However for the elite athlete or body builder, the muscle cells become more receptive to insulin compared to fat cells. This is the insulin response and varies from person to person. This response can be modified through diet and exercise.
The picture on the left shows the levels of blood glucose and insulin in the blood after consumption of food. Blood Glucose levels decline rapidly as Insulin binds to receptors on cells and facilitates the the passage of glucose in the blood to enter the cells. The low Blood Glucose levels turn off the stimuli to the Pancreas to secrete Insulin. Since the Insulin molecule is large, it declines at a very slow rate.
Looking at this chart, you can see that by mid morning you have Low Glucose Levels and High Insulin Levels. This high Insulin level is not good. When Insulin levels are high it binds with receptors on FAT CELLS. When FAT CELL receptors are bound with Insulin, it prevents the breakdown of FAT to FREE FATTY ACIDS for energy.
Since you can’t break down FAT to FREE FATTY ACIDS for energy, you now don’t have an alternate fuel source. Your Blood Sugar Levels are low, so you get hunger pangs at mid morning and you then eat more High Glycemic foods, which again elevate your Blood Glucose. Your day unfolds with persistently High Insulin Levels, which prevent you from metabolizing the FAT stored in your FAT CELLS.
On the other hand, if you eat a Low Glycemic Diet your day unfolds differently. By eating a Low Glycemic Diet, you prevent the Insulin spikes you noted in the earlier diagram. Therefore you do not bind Insulin to receptors on FAT CELLS which allows you to utilize the breakdown of FAT to FREE FATTY ACIDS as an alternate fuel source.
Another way to have low Insulin levels throughout the day is to eat less at each meal. The adage eat till you are 75% full DOES NOT WORK. You should eat till you are not hungry. This requires much less food at one go compared to 75% full. Just 3 mouthfuls of food is enough to assuage your hunger pangs. Naturally you will feel hungry faster, but that's ok. Just eat again when you are hungry. You'll find that you're spreading the same amount of food into 6 or more meals a day. Your Insulin levels will remain low because there is not all that much blood sugar circulating in your body from the small amounts of food you're eating.
So what all this means is that
- To avoid lipogenesis (fat accumulation), keep your Insulin levels low
- To keep your insulin levels low, eat foods with low GI/II
- Eat much smaller portions of food at each meal
- Eat till you are not hungry , not till you are 75% full
- Do not eat till you are sated
References
[1] An Insulin Index of Foods: The Insulin Demand Generated by 1000-kJ Portions of Common Foods. The American Journal of Clinical Nutrition 1997, Vol. 66: pages 1264-1276" by Susanne HA Holt, Janette C. Brand Miller, and Peter Petocz.
