Another slice of cake?

I'm watching CBS 60 minutes with Dr Sanjay Gupta telling us how sugar is poisonous and speaking to a doctor who is recommending that men eat less that 150 calories worth of added sugar per day, while women eat less than 100.  The report is interesting; the effects of just s sip of soda stimulates the same part of the brain as hard drugs like cocaine, and continued consumption of sugar lead to a tolerance similar to that experienced by drug addicts. In other words, the more  you eat, the more you are driven to eat.  The chemical at the heart of this is not picky.  However we get dopamine to release from brain cells, be in sex, drugs or rock and roll or now... sugar, we are driven to need more.   OK, so we eat a lot of sugar. So what?  As long as we reduce our fats, red meats, bacon, chips etc, we are basically OK- correct?  As long as we control our weight somewhat, and lay off the chips we should be fine- right? Not even remotely.  A study being discussed on the show, took young adults and carefully controlled their diets for a period of time while monitoring their physiology and biochemistry.  They had blood drawn and were scanned throughout the study period which had them eating a non-added-sugar diet for the first few days of the study, followed by a diet with 25% of their calories in the form of sugar; still a relatively low amount of sugar by American standards (on average we consume about a third of a pound a day).  Blood samples were drawn every 30 minutes and the added- sugar consumers showed significant increases in small dense LDL cholesterol (the bad kind that clogs the arteries) within two weeks of eating the diet with 25% sugar.   For those old enough, you might remember that in the 70s the government restricted fat in the diet.
There was a short term benefit, likely due to increased awareness of dietary causes of disease and the number of people who reduced their intake of saturated fates.  However, the effect was not sustained.  Doctors not he show suggested we have replaced that fat with carbohydrates, and refined sugar in particular.  As one researcher pointed out, food without fat tastes like cardboard, so the food industry upped the sugar content to keeps palates satisfied.  Now, cardiovascular disease is back on the increase and our children may be the first generation to have a lower life expectancy that their parents.

So the sugar in our diet does as least as much harm to our cardiovascular health as fat, and maybe more. But the story doesn't end there.  Obvious effects of increased sugar are obesity, metabolic syndrome, and diabetes, and all of these diseases have peripheral effects.  Less obvious is the effect of sugar on some cancers. Because sugar stimulates increases in insulin, it also catalyzed the growth of certain types of cancers.  Almost a third of common human cancers contain insulin receptors that circulating sugar latches onto and triggers the tumor cells to take up the glucose to use for cell growth.  Basically the tumor cells highjack our blood sugar and uses it to feed itself and grow.  Exactly whether the sugars in the blood cause the tumor to begin or just nudge it along once it has become established makes no difference.  Sugar is good news for cancer, and bad news for us.

There is much more to the sugar story that I'll save for other blogs but as we think about how to balance our diets, it's worth thinking about the role of the food industry in our food choices.  Since I still have the TV on, I'm catching a few ads I haven't seen before.  In one, Con Agra is encouraging us to buy their products and is promising one meal for a hungry child for ever specially marked package we buy.  This sounds incredible and I am sure there is good will behind the gesture. Certainly, there are too many hungry kids in America today. However, the foods that Con Agra is asking us to buy includes Snack Paks, frozen chicken nuggets, Chef Boyardee and others, all of which are high in sugar.  We buy and eat a package of processed food that will go a little way towards poisoning us (some might think that's too strong a word but based on what I have read and hear, I don't think so) and in return Con Agra will feed a child.  Does this make anyone wonder exactly how they will be feeing that child?

And finally, as I complete this blog, I just saw a fantastic commercial on the TV with a diverse group of vibrant people stripping open their coats and cardigans to unveil bright red shirts with 'I'm unique', I'm A Vailable, I'm a dreamer....etc, as they run, walk, dance, around some city. It seemed like such a positive commercial, celebrating all that is good in the world- courage, difference, creativity.  Imagine my disappointment when I realized what the ad was for.   Dr Pepper.  Ugh.

In 2012 I will be thin.... or will I?

The end is nigh.  Or so it seemed a year or two ago.  Now, it seems that the end of the world has gone off the boil and the race for the 2012 Republican nomination is eclipsing all talk of Armageddon.  As we begin this new year, millions of people are starting to act on new year's resolutions that will involve eating better, exercising more and possibly being nicer.  Working harder may factor in, and earning more is a no-brainer.  All of these will last at most a month or two and by Valentine's day the gyms will be empty and the larders stocked once again.   We humans are so predictable.  We love new beginnings but we are terrible at sustaining behavior change, especially if involves some effort, and getting fitter surely does.  Today on NPR, I heard Tara Parker-Pope (try saying that 10 times after a few beers) talking about her struggle with weight.  Tara is a health writer so for her to admit to weight issues is big and brave but the personal touch she brings to this story makes it convincing.  Her story, The Fat Trap, in this week's New York Times magazine and a telling  Q&A about it on line today, reports from the scientific literature on the memory of fat cells and their quest to keep themselves full.  She discusses the evidence that once a person becomes fat, their body will always try to maintain that weight despite all efforts to become slim.  A slim person who has once been fat will gain weight much more easily than someone of the same weight who has never been fat.  If this is true (and the article is compelling), then perhaps we should be less judgmental about people who start the fitness resolutions and then seem to give up so soon.

Researchers have shown that when women lost a significant amount of weight, even one year later, their levels of certain hormones were abnormal- ghrelin that stimulates hunger was unusually high, and peptide YY that usually suppresses hunger was below normal.  The cards were stacked against thee women even after they were no longer overweight.  A 2010 study found a number of gene variants that correlate with higher body-mass index.  One variant, known as FTO is carried in about 65% of Europeans and Africans, and up to 44% of Asians.  Whether we have one or two copies of this gene appears to correlate with weight and it seems that it may play a role in how we eat.  Genes, however, are likely only part of the problem.  Food cues are another.  We live in an environment that is saturated with food messages, images and cues to eat high fat, high sugar foods.   For people who have lost weight, their emotional response to food may be greater than slim non-dieters.  They also burn less energy than their non dieting counterparts for a given amount of exercise.

From all the data, it seems it's a hopeless situation, but Ms Parker-Pope feels it's better that she knows what she is up against and I feel the same way.  One of the surest ways to fall off the wagon is to have one day's blowout and then feel so bad you never get back on it.  Knowing that there are forces at work that your thin friend may never have to deal with, might actually strengthen the resolve to stick with the diet or the exercise plan.  Most importantly though, it seems we should not become overweight to begin with.  This underscores the value in educating children about balanced eating.  We need all the help we can get to maintain a healthy focus on food, diet, and exercise in the current world of information overload and dietary excess.  It's difficult enough to know what to eat and how much as an adult.  To teach our children to eat when they are hungry and to exercise as much as they can seems the responsible thing to do as a parent even though it's difficult with every other ad on TV being for some sugary or greasy snack.  For all of us, eating to satisfy hunger and getting out there and walking to work when we can, is a healthy prescription that we shouldn't sweat over, but just do our best whatever our biological odds.

Is this chemical making you fat?

Hormones are necessary chemicals that circulate in the bloodstream to keep our bodies running smoothly.  They regulate all bodily functions including sleep, sex-drive, moods and appetite although the precise mechanisms of their actions is imprecisely understood, and becomes perhaps more so as we gain more knowledge of all the moving parts.  In recent years,  the hormone leptin acquired a certain mystique for its potential role in the regulation of appetite.  Leptin reduces appetite but its effects are complex and people who are overweight or obese may become resistance to its actions.  The hopes of drugs to modify leptin have been somewhat confounded by the complexity of the system but new hope has arisen since the discovery of ghrelin, a hormone that acts as leptin's counterpart by stimulating appetite under certain conditions.  Ghrelin is considered to be the first circulating hormone that stimulates hunger.  It is increased before a meal and decreased during the meal so that as a person becomes full, the hormone levels drop and appetite is suppressed. 

Ghrelin's action is also very complex but a study released today by the Journal of Neuroscience (April 13th issue) provides an interesting new piece of data. It seems that ghrelin enhances the sense of smell, causing rats to sniff more often and smell more intensely. The investigators suggest that this may be an important mechanism to help animals find food when they are hungry.  When humans were given ghrelin in the same study, they inhaled air tainted with various 'flavors' more deeply than without ghrelin.  There was no difference, however, in how much they like the smells after ghrelin.  It seems ghrelin may make us more aware of potential foods around us but the effects of its evolutionary advantage in over-fed humans is not well understood. Evidence does suggest that ghrelin plays a key role in appetite regulation along with the other hormones, insulin and leptin. The big questions that may help us understand how to use these data to address the current obesity epidemic revolve around how to seperate our physiological drives to eat from the psychological ones.  David Kessler, former FDA commissioner, has suggested that the Western diet itself alters our body's ability to regulate our appetite and our food intake and these hormone likely have a critical role.  Once we get into the vicious cycle, it takes heroic efforts to break out of it.  With high calorie, processed food being cheaper and more accessible than more nutritious fare, it seems the odds are stacked against us.
As we understand more about the effects of particular foods on our responses to these 'hunger' hormones, perhaps we will find the evidence we need to regulate food production more appropriately so nutritious foods are more widely available at reasonable cost.  In the meantime, yet another study has shown that sniffing a certain food can actually decrease our appetite.  In women, just the smell of dark chocolate suppresses appetite and interestingly, it appears to be accompanied (or preceded?) by a change in circulating ghrelin in these subjects. 

Even with all the uncertainties of the system, it does seem that exercise and a reduction in calorie intake both work together to move the regulatory effects of leptin, insulin and ghrelin in a favorable direction.  So in other words, we can't go wrong if we walk a little more, eat a little less, and take a whiff of dark chocolate now and again.

Low-fat, low-carb-which is best?

The news is out. Low-carb is as good as low-fat for losing weight, and may be even better for your cholesterol. The Mediterranean diet is better for reducing fasting glucose according to the study that was published in the New England Journal of Medicine this week. In the same issue of the NEJM there is a book review on the latest thinking on Metabolic Syndrome, the collection of biomarkers that puts a person at high risk of diabetes and heart disease at the very least. Apparently about 60% of those over 60 years of age in the US suffer from Metabolic Syndrome (previously known as Syndrome X, and maybe now known as Dys-metabolic Syndrome) which manifests as abdominal obesity, high blood pressure, insulin resistance and an unfavorable cholesterol profile. The NEJM study showed the Mediterranean diet reduced fasting glucose, while the low-card diet yielded better weight loss and an improved cholesterol profile which made me think that either of these diet approaches could have far-reaching health benefits beyond weight loss if we took a closer look at what such diets do to Metabolic Syndrome as a whole.

The study took two years and participants appeared to remain compliant to the diets they were assigned. Weight loss was between 3 and 6kg for all groups with the least in the low-fat group and the most in the low-carb. The low-carb group, was the only group where calories were not restricted. Perhaps the low-carb diet curbs appetite in itself?

The article was interesting because it cobbled a sacred cow that says low fat diets reduce cholesterol. From this study it seems you are better off with low-carb to improve your cholesterol profile. The low-carb increased HDl and decreased LDL, whereas the low-fat diet had a negligible effect on LD although it did raise HDL.

The study has some flaws; it relies on self reporting for dietary compliance although relatives were instructed to encourage participants to stick to the plan. There were also few women in the study which is significant because the data did suggest some gender-based differences in effects of the three diets. Overall, I found the data interesting, and hope to see more of these longer term studies that study the effect of dietary composition on factors relating to weight and health. If 60% of us are truly suffering from Metabolic Syndrome, and hence will be looking for ways to slim down and de-fat our blood streams in the future, then the more of this type of study the better. Or maybe not. As Michael Pollan (author of In Defense of Food, 2008, The Penguin Press) might say, there should be little need to tell us what our bodies already know. We evolved to eat. Not too much, Mostly plants.

So why does it seem so hard?

Shai, I., et al., ., , . (2008). Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet.. New England Journal of Medicine, 359(3), 229-241.