Great Article!!
Which is Better for Health: High Carb or Low Carb?
August 17 2008
The effect of changing the macronutrient composition (protein, carbs & fat) to increase weight loss hasn’t shown anything to be excited about. It has been shown again and again that it is the total calories that matter and not the amount of fat and carbohydrates in the diet. However, the amount of protein, fat & carbs in diet has clearly shown to have an effect on cardiovascular disease markers, like insulin resistance, LDL & HDL, & triglycerides.
So if you had a choice will you pick a high carb or a low carb diet?
High carb or high fat?
It sounds pretty logical to assume that the easiest way to lower cardiovascular risk markers (triglyceride levels, VLDL, and so on) is to lower fat intake and increase carbohydrates in your diet. However, studies seem to show the exact opposite.
Number of intervention studies have shown people on a high carb diet (60-75%) to have significantly high levels of cardiovascular risk markers compared to a high fat diet (30-45%). And this has been shown in lean, obese and insulin resistant individuals.
It was believed that conversion of carbohydrates to fat only happens if people are in a positive energy balance and if they are eating insane amounts of carbs. But new isotope techniques have shown that the conversion of carbs to fat, though small, can even occur when the intake and expenditure are balanced.
But there is more to the story.
Low glycemic or high glycemic carbs?
So low carbs are better than high carbs, but can the type of carbs impact your cardiovascular risk markers? The earlier studies which did show increase in triglycerides and other markers used simple sugars as carbohydrates, which has a high GI (glycemic index). Apparently, the increase in triglycerides and all the bad stuff which happened with the high carb diet studies was due to the high GI carbs and can be eliminated with low GI and/or fiber rich diet. Though a low GI seems to be beneficial, there is no conclusive evidence to show that glycemic index of foods is highly important for healthy individuals. And there is a lot of controversy regarding the classification of foods based on GI.
The concept of glycemic index appears to be more important for insulin resistant and diabetic folks. High insulin levels with high carbs can, atleast theoretically, worsen the metabolic profile seen in insulin resistant and diabetic folks. As long as you are not chugging sugar and fruit juice for your carbohydrates, you don’t have to go crazy on low GI foods as some do.
Saturated or unsaturated fats?
Now let’s see if different fats have an independent effect on these above markers.
Lowering saturated fat and transfat and/or replacing saturated with unsaturated fats (polyunsaturated/monounsaturated or both) has shown to improve insulin resistance, lower cholesterol and LDL, increase HDL and lower risk of coronary heart disease.
As long as the fat is not exceedingly high (which makes it difficult to control calories), it is clear that the quality of fat matters a lot. Though there is some substantial evidence for polyunsaturated fatty acids (fish, canola oil, olive oil) for lowering heart disease, for some reason, routine dietary advice ( for ex., the nutrional pyramid) seems to emphazise the quantity rather than the quality of fat in the diet.
Conclusion
From the available data, it is not really clear if the general recommendation of 55-60% carbohydrates ( high carb) for healthy individuals is the optimum ratio for general health. And considering the prevalence of insulin resistance and the easy accessibility to high GI foods and drinks in our society, I would personally lean towards a moderate carb (40-45%) diet.
General Recommendations
1 | Keep your saturated fats below 10%.
2 | Keep your total fat level betwen 25-45%.
3 | Most of your fat should be from unsaturated fats, preferrably omega-3’s (fish, canola oil, olive oil)
4 | Limit your cholestrol intake
5 | Get your carbs mostly from vegetables, fruits, legumes and whole grains.
6 | And don’t forget to exercise.
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Anoop | Tue August 19, 2008
Thanks.
Nutrition science is freakin hard.
People often argue or try to pin it down to one variable like cholestrol, or LDL. But the fact is that there are so many variables (HDL, cholestrol,insulin resistance, homocysteine,endothelial dysfunction inflammation..),and more to be discoverd in the future, that you need some large randomized controlled trials to see if diet changes indeed affects CHD directly. And these type of trials with thousands of subjects lasting 5-10 yr duration are just really hard.
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