Accumulated weight around the mid-riff (abdominal fat) is associated with an increased risk of chronic conditions including cardiovascular disease and type 2 diabetes. One of the mechanisms that may cause the build-up of fat around the middle concerns secretion of the hormone insulin, which is produced principally in response to rising levels of sugar in the bloodstream that come from consuming carbohydrate in the diet. Carbohydrates that are most disruptive in terms of blood sugar (high glycaemic index/load carbohydrates) are the ones most likely to cause surges of insulin that can cause people to pile on the pounds around the middle. I don’t suppose it’s any surprise therefore that these carbs are also associated with an increased risk of cardiovascular disease and type 2 diabetes (see here and here).
However, the biochemical disruption wreaked by blood sugar-destabilising carbohydrates has been linked with an increased risk of other conditions too. For example, the second link above goes to a discussion of the study which finds and association between high GI and/or GL diets and increased risk of gallbladder disease and breast cancer. In recent times, evidence has also linked disruptive carbohydrates with an increased risk of age-related macular degeneration (AMD) ” the most common cause of loss of vision and blindness in adults. See here and here for the details of two relevant studies.
Bearing all these strands of evidence in mind, then one would predict that the extent of abdominal fat would have some association with risk of AMD. A study published this month in the Archives of Ophthalmology examined the association between changes in the waist-to-hip ratio (a measure of abdominal obesity) and risk of AMD in middle-aged men and women over more than 6 years [1]. At the end of study, higher waist-to-hip ratio (WHR) was associated with elevated risk of AMD. What was also interesting is that individuals who saw a decrease in their WHR generally saw a reduction in risk of AMD too. Overall, a 3 per cent or more decrease in WHR was associated with a 29 per cent reduced risk of AMD.
The authors of this study went further by sub-dividing the study population in individuals of ‘healthy’, ‘overweight’ and ‘obese’ weight categories. The reduction in risk of AMD coming with reduced WHR was only seen in individuals in the obese category (BMI 30 or more). In these individuals, a 3 per cent or more reduction in WHR ratio was associated with a 59 per cent reduced risk of AMD.
Epidemiological studies like this one cannot be used to conclude that losing weight around the middle helps protect against AMD. However, the consumption of high GI/GL foods is associated with AMD, and eating of less of them may reduce the risk of AMD. A diet lower in disruptive carbs generally helps trim the waist too. Put all this together, and I reckon there’s a good argument for the notion that eating a diet low in blood sugar disruptive carbohydrates may help individuals preserve their vision in later life.
References:
1. Peeters A, et al. Changes in Abdominal Obesity and Age-Related Macular Degeneration: The Atherosclerosis Risk in Communities Study Arch Ophthalmol. 2008;126(11):1554-1560
