Why too much sugar is bad for us?

It seems that every one agrees that too much sugar is bad for us. However, nobody agrees how much is too much and why?

First of all, sugars are empty calories.

Secondly, we are not the only ones who like sugar. Some bacteria inhabiting our body but harmful to us seem to like sugar as well.

We all know the sugar causes tooth decay. After eating sugar, sticky glycol-proteins start to adhere to the teeth. At the same time, millions of bacteria known as Streptococcus mutans also adhere to the glycoprotein. In the next stage, the bacteria use the fructose in a metabolism process of glycolysis for energy. The end product of glycolysis under anaerobic conditions is lactic acid. The lactic acid creates extra acidity to decrease the pH to the extent of dissolving the calcium phosphate in the tooth enamel leading to the start of a cavity. That’s what sugar does to our teeth.

Helicobacter pylori, the bacteria that cause a chronic low-level inflammation of the stomach lining and are strongly linked to the development of duodenal and gastric ulcers and stomach cancer, seem to love glucose as well (see here).

Most importantly, sugar (which includes simple sugar, disaccharide and refined starch) raises the blood glucose level rapidly, which in turn triggers the release of insulin. Too much sugar intake means rapid fluctuations of blood sugar level, which is not healthy because of the stress they place on the body.

In addition our overall wellness and longevity seem to be closely connected to insulin signaling pathway. Metformin, a drug to treat type 2 diabetes, seems to show promise as a calorie restriction mimetic in the worm C. elegans (see here).

Now we have established that too much sugar is bad for us. How much is too much? I have already cut out processed mono- and disaccharides in my diet. If the sugar you eat comes from whole foods (fruits, vegetables and grains), can you still eat too much sugar (carbohydrates)? The answer is yes and very controversial. There exist two camps on the nutrition frontiers, one promotes low carb and another promotes low fats. There is practically no agreement between the two.

In the end, I decided to calculate backwards in order to find out how much carb. I should eat. I set my daily caloric intake at 1600. My protein intake I decided is 46 gram (1 g per kg of body weight) daily. My fat intake I set at 50 gram.

Fat 50g x 9 = 450 calorie ÷ 1600 = 28%
Protein 46g x 4 = 184 calorie ÷ 1600 = 12%

Therefore, my carbohydrates intake is 100% - 12% -28% = 60%
60% x 1600 = 966 calorie ÷ 4 = 242 gram of carbohydrates daily.

Of course, the ratios are there only as a goal to strive for. In reality, the total amount of calorie intakes varies from 1400 to 1800 a day. Fat intake varies from 20 to 35%, protein from 10 to 20% and carb from 45 to 60%.

Of the above numbers, most nutritionists will agree to the amount of protein I intake.

For the low fat camp, 50g of fat or 28% of total calorie is way too much. As for the low carb camp 242g of carb. or 60% of total calorie is a horror story.

However, growing up in a starving China, and having seen many women lived past 90 on mostly carb diet, it is very difficult for me to accept that high fat diet is healthy. In addition, how do you eat only the fat part without taking in too much protein? In addition, a lot of goodies such as fibers, vitamins and anti-inflammatory phyto-chemicals are associated with carbohydrates.

So I will eat carb, be it rice, pasta, bread, vegetables or fruits as long as non of them contains added sugar or vegetable oils.