Every third child going to private schools in the Delhi area is obese. This is the statistic released last year by the National Diabetes, Obesity and Cholesterol (N-Doc) survey of the Diabetes Foundation of India. Is it that obesity is related to the family income or prosperity, and kids from richer families tend to be fatter? Not quite.
Even among the children going to government schools, every tenth one is obese, and the number is climbing by the year. Obesity is becoming an epidemic. Obesity begets disorders such as diabetes and high blood pressure.
Why has this happened? High-fat and high-sugar food, plus more couch-potato habits and less exercise. The family lifestyle itself appears to be a factor. With both parents working and kids attending pre — and post — school tuitions and coaching classes, family life starts from early mornings and extends into late evenings.
They tend to eat late, watch prime time TV and hit the bed late, often just after a nightcap of sweetened or chocolate milk; likewise in the early mornings. Our life style is far different from those of our parents and grandparents. We are turning out to be fatter than them.
Obesity is a health hazard and must be countered. So do we start giving our children medicines and push them to do exercise? The latter — yes, but the former — is that the only way? Are there not non-pharmacological solutions to fight obesity? This is the question that Professor Satchidananda Panda of Salk Institute at La Jolla, California has been addressing for quite some time.
Professor Panda has been studying the physiological and metabolic aspects of the day-night cycle, or the circadian rhythms of life forms. It is not us animals alone, but even plants, indeed most life forms on earth, have daily cycles of activity.
Three years ago, he and his group showed that several genes in our bodies are active in a diurnal rhythm. Using the mouse as the experimental model, they showed that certain genes in the liver are more active during the wake-up period when the mouse is active than when the animal is resting (PNAS 2009; 106, 21453).
Some of these genes are switches or regulators. One of them codes for an enzyme called AMPK, which helps in regulating or adjusting the metabolic energy in a dynamic equilibrium, much as a valve or a siphon does.
Another called CREB produces a molecule which binds to specific spots on the DNA, regulating the activity of other genes “downstream”.
A third named AKT regulates the metabolism of glucose, and also the clearance of useless or dead cells. Professor Panda found that these genes actually go through a day-night cycle in their activity.
In effect this means that the way we use metabolic energy, or the feed-fast cycle is intimately coupled to, or regulated by our genes, which display their own 24-hour rhythm of activity.
How does this translate into the eating pattern of the mouse? Panda and his group put two groups of mice on different eating patterns for over 3 months. Both groups were fed the same high-fat, high-calorie diet (the mouse equivalent of double burger, fries and cola).
Group A could eat however much they wanted, and whenever — be it day or night. The second group were fed the same food, the same amount, but fed only at night (mice are night animals) and restricted to 8 hours. And they compared the health indicators — obesity, inflammation, liver condition, blood sugar, cholesterol and other parameters of animals in group A and B.
The results were astonishing. Both groups ate the same high-fat high-calorie food, and ate to their heart’s content. Yet the ones who were allowed time-restricted feeding were 40 per cent leaner than the group A, and healthier.
The latter, in contrast, were obese (45-50 grams versus 30 grams after 18 weeks), and had higher cholesterol and blood sugar levels. Time-restricted feeding appears to improve body rhythms, cut down obesity, lipid levels, liver damage, alleviate inflammation and improve glucose metabolism as well as bile acid levels. A commentator who has blogged Prof. Panda’s paper (which appears in Cell Metabolism, June 6, 2012, pp. 848-860) succinctly puts it: “It is not what you eat, but when you eat”.
I contacted Prof. Panda about this remarkable paper of his and he pointed out how our body is not a 24/7 factory but is more efficient in burning fat or using energy at certain times of the day and less efficient in utilising them at other times.
He further writes that for millions of years, we humans ate mostly during the daytime. So our genes and metabolism are hardwired for overnight fasting. It is only in the last 40-50 years have we started changing our daily routines and eat non-rhythmically.
A few additional hours of fasting time daily, he says, can add a few years of healthy lifespan. Overall, obesity and diabetes are diseases of prevention — not of cure. Thus, what we need to do in order for a healthier, leaner, longer life is clear.
True, people have long held that eating less at nights, missing a meal every week and so on are healthy. What the Panda paper offers is the molecular and physiological explanations for such practices.
True, mice are not men. Similar experiments need to be done using human volunteers. And Prof. Panda is keeping his fingers crossed until such a human trial is carried out — and is looking for collaborators in India. I suspect our Department of Health Research would be interested.