Dr. Sharma's Obesity Notes

While in India, I have plenty of time to read the Indian newspapers and magazines, that have circulations Western publications can only dream of.

Not surprisingly, “health and beauty tips” are a staple feature with articles proclaiming the benefits of everything from yoga to bariatric surgery.

And of course, when it comes to traditional Indian herbs or spices, almost every ingredient is offered as a panacea.

Here, for example, are the virtues of using coriander (dhanya or cilantro), a commonly used spice and garnish (taken from a recent article in the Times of India):

- It lowers blood sugar levels

During my current visit to New Delhi, it is hard to overlook the substantial increase in the prevalence of obesity in Indian men and women. While this may not be the phenotype that immediately comes to mind when thinking of India, there is no doubt that obesity prevalence is continuing to rise at an alarming rate.

Recent evidence for this comes from a study published by Chopra and colleagues from New Delhi, published in a recent issue of the European Journal of Clinical Nutrition.

In this systematic review of obesity in Indian girls and women were found to have consistently higher obesity rates than Indian boys or men.

Interestingly enough, abdominal obesity, sometimes referred to as ‘male-pattern’ obesity is in fact more common in Indian women than in men.

Not surprisingly, this increased rate of obesity is reflected in an increasing prevalence of type 2 diabetes that was reported to be as high as 14% in the 2001 National Urban Diabetes Survey.

Clustering of cardiovascular disease risk factors was further increased in post-menopausal women, not least due to a number of factors that may be of particular relevance in Indian women including sedentariness and overly caloric diets.

How exactly these increasing rates of obesity can be addressed remains anyones guess. While it is easy to see the proliferation of “slimming-centres” and “spas” at every corner, as in the West, these centres often provide little long-term help and of course generally do not cater to the folks, who would likely benefit the most.

Needless to say, the medical system in India, is as overwhelmed and insufficiently prepared to address obesity, as we are in the West.

Clearly a challenge if I ever saw one.

AMS
New Delhi, India

I am currently in New Delhi enjoying daytime temperatures of 45 degrees Celsius – I’d forgotten how hot this can be.

A good opportunity to take a look at recent literature on obesity in India, where this is clearly becoming an increasing problem – India now has the largest number of people with obesity (using the South Asian definition of BMI 25)  and perhaps the most people living with diabetes anywhere in the world.

An article that caught my eye is the recent analysis of the relationship between the consumption of milk and milk products and obesity by Satija and colleagues from the Public Health Foundation of India, New Delhi, published in PLoS One.

As anyone familiar with Indian cuisine is well aware, milk in its various forms including plain milk, in tea (where tea leaves are traditionally boiled at length in watered down milk), curd, and buttermilk (often consumed as lassi) is considered a staple of the Indian diet and apart from lentils (another staple), often the only significant source of protein for the vegetarian masses.

Information on dairy consumption assessed using a Food Frequency Questionnaire was obtained from the cross-sectional sib-pair designed Indian Migration Study (3698 men and 2659 women), conducted at four factory locations across north, central and south India.

After controlling for potential confounders, the risk of being obese (BMI≥25) was almost 50% lower among women among those who consume one or more portions of plain milk daily than those who did not consume any milk.

On the other hand, daily tea consumption of more than one portion was associated with a 50% increased risk of obesity and increased waist circumference in men but not among women.

There was no association between curd and buttermilk/lassi consumption with obesity and high waist circumference among either men or women.

Thus, there appears to be an inverse association between the daily consumption of plain milk with the risk of being obese, but the authors hasten to add that this is merely an association and does not imply causality. In plain english, this means that we should not rush to conclusion that decreased milk consumption should be added to the list of possible causes of obesity in South Asia or that drinking more milk will help my Indian brethren lose weight.

On the other hand, given that there are several reasonable hypotheses linking adequate dairy intake to energy homeostasis, this is certainly an issue that may require further study.

I do recall that my grandfather, who lived to be a 104 and was always thin as a rail, would never go without his daily glass of warm milk before bedtime (but he’d also go for long brisk walks at 5 am every morning – so no conclusions can be drawn from this n=1 case study).

AMS
New Delhi, Arya

Unbeknownst to many readers, the first 10 years of my research career was built largely on studying the effects of salt (or rather sodium chloride) on blood pressure.

In over 40 peer-reviewed publications, we described in excruciating detail the physiological effects of increasing and decreasing sodium intake, in many cases using single-blind randomised trial designs in hundreds of volunteers.

We not only examined the effects of salt on blood pressure but also on a wide range of physiological, metabolic and psychological parameters. We studied the effects on acid-base balance, we conducted genetic studies, we even performed in vitro studies on cells cultured from “salt-sensitive” and “salt-resitant” individuals.

In many respects, these studies left me as confused about the role of sodium on these parameters as I was before. Not that we did not report findings that helped us better understand the complex physiology of sodium homeostasis – it is just that we failed to convincingly demonstrate any major health implications of these findings. In some cases we even reported adverse consequences of sodium restriction resulting both in significant elevations in plasma lipids and insulin resistance (perhaps not surprising given that reducing sodium intake markedly stimulates both the sympathetic and renin-angiotensin systems – the very systems we seek to block to reduce cardiovascular risk).

That was almost 20 years ago – the field does not appear to be much clearer today.

Thus, although surprising to some, I must admit that I was by no means surprised by the report on sodium released last week by the Institute of Medicine, with the rather revealing conclusion that,

“…the evidence from studies on direct health outcomes was insufficient and inconsistent regarding an association between sodium intake below 2,300 mg per day and benefit or risk of CVD outcomes (including stroke and CVD mortality) or all-cause mortality in the general U.S. population.” (or any other population for that matter)

This is not to deny that despite considerable methodological problems (not least in the actual measurement of salt intake), there is evidence to support the idea that higher salt intake may affect blood pressure and possibly cardiovascular risk. However, the data is certainly  far less conclusive than food bloggers and health activists would lead us to be believe.

Not surprisingly, the same activists and organisations are now up in arms stopping just short of criticizing the scientific credibility of the IOM expert committee – no doubt, the same folks would have been applauding the conclusions of this “illustrious panel”, had the findings been more in line with their own activist agendas.

What is perhaps even more infuriating to those who have always considered the issue of sodium recommendations a slam-dunk case is the statement by the IOM that, there is in fact no basis on which to draw recommendations for the general public in recognition of the fact that significant proportions of the population may require higher sodium intakes and may even be likely to suffer harm from overly enthusiatic sodium restriction.

While I have no illusions that this report will in any way put the century old debate to rest (indeed the report calls for further research), I think that there is a much bigger message in this report that should let us tread cautiously when it comes to dietary recommendations in general.

Let us remember that associations (on which so many of our assumptions about healthy diets depend) simply do not prove causality, even when backed by seemingly plausible biological hypotheses derived largely from rodent toxicology. We should also remember that fancy statistical predictions on the vast number of lives lost or saved by altering the population intake of this or the other nutrient, are generally based on sometimes rather heroic assumptions that may well explain whey they are rarely (if ever) borne out by actual interventions.

Thus, whether we are talking about salt, fat, carbs, sugar, fibre, gluten, calcium, Vit D, dairy or red-meat, a degree of humility in advocating for policies and other measures to reduce or increase this or the other is generally in order.

Seldom in the field of nutrition are things as cut and dried as some will have us believe – if only food were as simple as tobacco.

AMS
New Delhi, India

Disclaimer: I was invited to be on the IOM Expert Committee but had to decline due to other obligations.

As not everyone may have a chance during the week to read every post, here’s a roundup of last week’s posts:

• Skeletal Muscle as an Endocrine Organ
• Nudge, Nudge – Wink, Wink: Changing Health Behaviours
• Developments in Obesity Treatment Session, ECO 2013
• Restoring Energy Balance in Communities
• Prohibition Drives Fast Food Underground?

Have a great Sunday! (or what is left of it)

AMS
Frankfurt, Germany