Saturday, 8 August 2015

The Sugar Debate – Confusing and Unhelpful Developments

I was surprised by the news of the mooted official recommendation that we should reduce our sugar intake by a factor of two – consume no more than 25g sugar, added and naturally occurring, per day.  Presumably this is to control the obesity epidemic and tooth decay.

I have seen and heard many silly things in my life but this advice, if true, is definitely the most outrageous for its effect on destabilising the general public.  The reasons are not difficult to understand and that is why I find it amazing that experts, who should know better, are failing to comprehend the science and psychology of eating and how people react to lifestyle changes.

In developed countries, over the past 30 years or more there is no correlation, in fact there is a strong inverse correlation, between increase in obesity and sugar consumption.   I have been involved in scientific research for more than half a century and I cannot understand the sense of reducing sugar consumption by 50%.  May be the experts know something that is not easy to reach and understand but then I am used to delving into latent information in data and I can’t find much to go on – I am confused.  How will an average person understand this advice is beyond comprehension?

The current guidelines are 50g (10% of recommended energy intake) per day.  For my lifestyle – most meals are cooked at home from fresh ingredients, we drink water with most meals, no sugar in tea and coffee – we are just about there in sticking to the limit.  Most fruits bring in 10g naturally occurring sugar and with five fruits a day, it is already 50g with no margin left.  Reducing intake of sugar to 25g will require a drastic change in the eating habits and associated lifestyle changes.  Nobody likes changes in the way they do things – it causes stress, headache – might induce trauma, can make you feel depressed, can give you skin problems and whatever else.  This recommendation is prescribing all of these to the whole nation.


As any nutritionist will tell you that the following equation holds (over long term):


Energy in – Energy used = Change in Weight

If you eat too much and do not burn it by some activity then you will gain weight and vice versa.  It does not really matter in what form the energy intake is (fat, carbohydrate or protein), the body will eventually obey the equation.
Most carbohydrate is converted to some type of sugar as a first step in digesting the food and the recommendation for daily carbohydrate consumption is about 250g. We all eat foods like potatoes, bread, rice that are rich in starch (carbohydrates). It is interesting to see how these foods affect the body when we eat them.


The first step in digesting the food is to break down the complex carb molecules to simpler glucose molecules and this already starts when you are chewing the food.  Starch is converted to glucose (a type of sugar readily absorbed by the body). Glucose molecules go into the blood stream and are responsible for increasing the blood sugar level for a short time until insulin released by the body metabolises it to produce energy.  If you are diabetic, insulin might be in short supply and the blood sugar level stays high for longer.  You need medication to help the metabolic process.


The longer blood sugar levels stay high the greater are your chances to become diabetic in due course.  If the food you eat spikes the blood sugar level higher then it will take longer to return to normal and it is considered bad for your health.  They actually have a measure of the spike – the Glycemic Index (GI) which is used as a good predictor of a carbohydrate’s effect on blood glucose.  GI of a food is a number measured relative to glucose of the same weight.

Glucose has a GI of 100.  Some other carbohydrates have GI as follows:
Sugar 68; White Bread 70; Baked Potato 85; White Rice 64 etc.
The more important number is Glycemic Load (GL) which is how an average portion of the particular food will affect your blood glucose level. 
This is listed in the table below  http://nutritiondata.self.com/topics/glycemic-index
Glycemic Indexes and Glycemic Loads for Common Foods
GI and GL for Common Foods
Food
GI
Serving Size
Net Carbs
GL
Peanuts
14
 4 oz (113g)
15
2
Bean sprouts
25
 1 cup (104g)
4
1
Grapefruit
25
 1/2 large (166g)
11
3
Pizza
30
 2 slices (260g)
42
13
Low fat yogurt
33
 1 cup (245g)
47
16
Apples
38
 1 medium (138g)
16
6
Spaghetti
42
 1 cup (140g)
38
16
Carrots
47
 1 large (72g)
5
2
Oranges
48
 1 medium (131g)
12
6
Bananas
52
 1 large (136g)
27
14
Potato chips
54
 4 oz (114g)
55
30
Snickers Bar
55
 1 bar (113g)
64
35
Brown rice
55
 1 cup (195g)
42
23
Honey
55
 1 tbsp (21g)
17
9
Oatmeal
58
 1 cup (234g)
21
12
Ice cream
61
 1 cup (72g)
16
10
Macaroni and cheese
64
 1 serving (166g)
47
30
Raisins
64
 1 small box (43g)
32
20
White rice
64
 1 cup (186g)
52
33
Sugar (sucrose)
68
 1 tbsp (12g)
12
8
White bread
70
 1 slice (30g)
14
10
Watermelon
72
 1 cup (154g)
11
8
Popcorn
72
 2 cups (16g)
10
7
Baked potato
85
 1 medium (173g)
33
28
Glucose
100
 (50g)
50
50
Glycemic Index (GI) and Glycemic Load (GL) for a few common foods.
GI of 55 or below are considered low; 70 or above are considered high.
GL of 10 or below are considered low; 20 or above are considered high.
One can’t help to notice that sugar is not very important in spiking the blood glucose level while potato and rice based dishes are the most effective.
The question is  - why target sugar intake when everything else is as important, if not more so?
I have not talked about other possible actors that might be responsible for increase in obesity in developed countries (may be subject of another blog).  Things like our sedentary lifestyle – we are not as active now as we used to be thirty or forty years ago.  Children, in particular do not play outside much and sit in front of TV etc.  Then the modern lifestyle creates more stress – lot of people deal with stress by eating more and the equation tells us that they will gain weight. 


I have said my bit – let me know your thoughts about this very important matter.

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