Could Sunlight Aid Weight Loss?

Nayak et al. have recently published the findings of their fascinating research into the effects of light on fat metabolism in mice.

Animals have adapted to use light in various ways. The most obvious is our sense of sight – it creates images in the brain through the detection of photons by light sensitive proteins (opsins) in the retina. But there are also non-visual ocular photoreceptors that help regulate our circadian rhythms (body clock), pupillary light reflex and eye development. Interestingly, light sensitive proteins are also found outside the eye. Opsins in our skin can regulate the circadian clock and others can influence blood vessel dilation. In birds, it’s photoreceptors deep within the brain that regulate seasonal breeding behaviour.

There have been suggestions that adipocyte (fat cell) function may be modulated by light. White fat (WAT) acts as a storage site whereas brown fat (BAT) generates heat through a process called non-shivering thermogenesis (NST). During lipolysis, white fat can be broken down into free fatty acids (FFAs) and glycerol. The brown fat can then use the FFAs to generate heat by oxidation. This process plays a crucial role in the regulation of body temperature during cold exposure.

In the current study, Nayak et al. found that lipolysis was brought about by the exposure of light receptors within white fat (encephalopsin, OPN3) to light. OPN3 was particularly sensitive to blue light. The mice lacking OPN3 or light exposure had diminished heat-generating responses when placed in cold environments. The authors conclude: “If the light-OPN3 adipocyte pathways exist in humans, there are potentially broad implications for human health. Our modern lifestyle subjects us to unnatural lighting spectra, exposure to light at night, shift work, and jet lag, all of which result in metabolic disruption. Based on the current findings, it is possible that insufficient stimulation of light-OPN3 adipocyte pathway is part of an explanation for the prevalence of metabolic deregulation in industrialized nations where unnatural lighting has become the norm.”

BBC Horizon’s – Eat, Fast And Live Longer

Another great programme from BBC Horizon presented by Dr Moseley. He starts off the programme by following the oldest man to complete the London marathon…a 101 yr old sikh who is healthy and takes no medication…the typical 65 yr old european takes 6 pills a day! The centenarian attributes his good health to his diet and more specifically his small portion size…about half of a normal adult”s.

This is not the first time that caloric restriction has been linked to longevity. In the 1930s, during the great depression in the US, although there were widespread food shortages…surprisingly life expectancy increased by 6 years. During the same period scientists at Cornell University found that animals on restricted diets lived longer.

Dr Moseley had a keen personal interest in the subject because of the threat of disease due to elevated blood sugar and cholesterol. He traveled the US speaking to the most eminent specialists in the field in a quest for a solution to his health problems. His first port of call was Professor Luigi Fontana from Washington University and Salerno Schools of Medicine. Prof Fontana advised a diet low in calories but high in nutrients and introduced Dr Moseley to Joe. Joe was in his 50s and had been on 1900 kcal/day for about 10 years. His body fat was 11.5% whereas Dr Moseley”s, also in his 50s, had a body fat % of about 27. Although the benefits were clear, Dr Moseley wanted to understand the mechanism in the hope of being able to draw the benefits without having to do any of the hard work! This is one of the reasons I like his programmes…his attitude is typical of the average european (or american)…we want results quickly, with as little effort as possible…sound familiar?

He then met up with Professor Valter Longo at the University of Southern California. Prof Longo showed him a special mouse…about half the size of a normal mouse…but incredibly it had a lifespan that was 40% longer…the equivalent of 120 human casino jameshallison years! The mouse had been genetically modified to have low levels of the a growth hormone called Insulin-like Growth Factor 1 (IGF1). IGF1 is thought to be the link between calorie restriction and longevity. There are about 350 people worldwide who have genetically inherited low levels of IGF1. Their condition is named Laron syndrome and although some of them smoke and eat what they want, amazingly they don”t get diabetes or cancer! Low levels of IGF1 seem to increase cell repair and decrease cell division (which probably accounts for their extremely small stature).

Protein has been found to increase our metabolism and put us in “go-go” mode but the downside is that it decreases cell repair. Three things can help decrease levels of IGF1: decreasing calorie intake, decreasing protein intake and lastly, the most effective way…is by fasting. Fasting can dramatically reduces levels of blood glucose and IGF1 within as little as 24 hrs. Obviously fasting can be dangerous and should only be undertaken if in good health and under close medical supervision. So Dr Moseley decided to give it a go for 3.5 days. He only allowed himself water, black tea and a 50 kcal soup each day. As expected, his blood sugar decreased significantly and his IGF1 levels halved. Unfortunately, the effects are only temporary and one would need to decrease protein intake and fast every couple of months to maintain changes…not for Dr Moseley, so he continued his search…

Dr Krista Varady from the University of Illinois at Chicago had a much more palatable proposition…eat as much of whatever you want on one day and eat a reduced amount of whatever you want the following day…feed day, fast day, feed day, fast day, etc. It”s called Alternate Day Fasting (ADF). On the fast days women are advised to eat 400-500 kcal and men 500-600 kcal. Preliminary trials with overweight subjects are showing promising results including weight loss, lower levels of bad cholesterol and fats in blood and decreased blood pressure.

Lastly, Dr Moseley paid a visit to Dr Mark Mattsen from the National Institute on Aging in Baltimore. He has conducted animal experiments on intermittent fasting and has found that it postpones the development of Alzheimer”s and senile dementia like diseases. Sporadic bouts of hunger seem to trigger the growth of new neurones! In evolutionary terms, this would have provided a survival advantage in times of famine. Intermittent fasting has better effects on the brain than daily calorie restriction. Dr Mattsen suggested alternating 5 days of normal eating with 2 days of fasting. So Dr Moseley gave it a go for 5 weeks. On the normal days her took in around 200 kcal and on the fast days he ate about 600 kcal. Please bear in mind that normal calorie intake is based on sex, height, weight and activity. The results were extremely impressive. He managed to lose 1 stone and decrease his body fat from 27% to 19%! His blood sugar levels decreased to within normal limits, his IGF1 levels halved, his total cholesterol decreased and his good cholesterol increased. I assume that although he could have eaten whatever he wanted, he was sensible about it.

Dr Moseley ended the programme by saying that it was “the most interesting journey that I”ve ever been on…and I”ve never said that before”.

The Obesity Paradox

According to research, obesity is to a certain extent genetically determined. The pandemic now affects a billion people and has gradually grown over the last 150 years. Interestingly, our genes have not changed over that period. So how could obesity, which is genetically determined, have appeared over a time when our genes have remained unchanged? What has changed?

Well, over 150 years ago 90% of the population lived an agricultural lifestyle. They walked to work, performed active physical work, walked home after work. Water had to be carried and clothes washed by hand. Our lifestyles were much more similar to those of our distant ancestors in that, we stood and walked for most of the day.

With the advent of industrialisation and urbanisation 50% of the world’s population moved to the cities. This figure is even higher in developed countries. Factory work became prevalent and chair-based work replaced standing just like machine operation replaced tool use. The biggest change has taken place over the last 25 years…over half the population in the developed world now sits in front of a computer for 8 hours a day. As a result of these changes, our occupational energy expenditure could have decreased by as much as 1200 kcal/day.

At home most of us have a personal computer and we spend a few more hours banking, shopping, browsing and even socialising (Facebook, Twitter, MySpace, etc)! Oh, and if we’re not sitting in front of the computer it’s probably the television…another brilliant invention that appeared in the last century. Sales of labour-saving devices like washing machines, dishwashers and cars track obesity rates and it’s estimated that mechanisation saves  around 111 kcal/day.

Obviously food has become more available (in industrialised countries) and one could assume that our intake has increased. Surprisingly, in the UK since the 1980s, energy intake seems to have decreased whereas obesity rates have doubled! Statistics in the US show that intake hasn’t changed but obesity has skyrocketed…

Here’s a quick thermodynamics refresher…when energy is added to a system it’s either used to perform work or stored…if the energy intake is greater than the energy expenditure, the excess is stored as fat…if the energy imbalance continues over several months or years it leads to obesity. It’s becoming clear that it’s the decrease in our activity that has lead to the weight gain.

How come we haven’t all been affected by this? This is where the genetics plays it’s part. Those of us that are genetically programmed to conserve energy have blossomed in this new modern environment, the rest have found other ways to replace their need for movement: walking or cycling to work, pacing about at work, getting involved in DIY at home, going to the gym or taking part in sports or active hobbies. Crucial research shows that lean sedentary people stand and walk for about 2.5 hrs/day more than obese people. If obese individuals were to stand and walk 2.5 hrs more each day it would equate to an expenditure of 350 kcal/day which is exactly the figure that was identified in a different study to determine the amount of exercise that obese people had to undertake to help weight loss.

Why should we care about obesity? Perhaps because it’s been linked to type 2 diabetes, hypertension, stroke, arthritis, sleep apnea and cancer…maybe because obesity related medical expenses are out of control and  in the US they reached $75 billion in 2003!

What’s the best way to lose weight? Is it through exercise or non-exercise activity? Or both? According to Dr Levine, the majority of people who exercise for just under 2 hours a week expend an average of about 100 kcal/day. This is a drop in the ocean compared to what it’s possible to achieve by increasing non-exercise activity. Granted, we can’t all change our jobs and become lumberjacks or tree surgeons but we can become more active both at work and at home. Our muscles are almost completely silent when seated and as a consequence, our energy expenditure is negligible…our expenditure goes up 15% when standing and doubles when ambling…purposeful walking can double or triple it! So, spending less time sitting seems to be the key to burning up more calories.

Prolonged sitting time has been linked to metabolic syndrome, type 2 diabetes, obesity and cardiovascular disease. This is thought to be the result of poor fat metabolism due to the decreased production of lipoprotein lipase in muscles when seated. Non-exercise activity reverses this process.

It appears our technological innovations have had insidious effects on our health. The antidote lies in freeing ourselves from the chair…can we afford to wait for governments and corporations to reengineer our workplaces? Probably not…we must all take responsibility for our health and those among us that have a predisposition towards energy conservation need to take active measures by simply standing and walking about more often and for longer periods during the day.

Most of the information in this post is inspired from the work of Dr James Levine, Professor in the Department of Endocrinology at the Mayo Clinic in Rochester MN

Exercise Encourages Healthy Eating

Researchers have recently postulated that exercise may help encourage healthy eating! How? By changing the structure and function of the brain! The result of which is an enhanced inhibitory control. What this means in layman’s terms is that we no longer have to succumb to the temptation or lack of restraint that causes our over indulgence in food.

So, in addition to increasing our metabolism and burning more calories, exercise also improves our diet. What are you waiting for?