In parts one and two, I wrote about why I don't like fatties, and explained a little about the advancement of evolutionary medicine. Today, I will touch on three topics that may help us understand our addiction to sugar: evolution, our biochemistry, and hormones.
Sugar has not been a part of humanity’s diet throughout our history. In fact, it is only during the last 200 years that refined sugar has been available at all. Our ancestors’ only exposure to the type of sweetness we take for granted in most of our foods today was the occasional seasonal availability of honey (apparently, fruit was nowhere near as sweet back then). This scarcity forms the thesis of the theory that many paleo proponents promote today.
From an evolutionary standpoint, it is thought that perhaps some folks were better able to handle the occasional sweet treat, such as honey or the occasional sweet fruit, and would be better able to store the excess carbohydrate energy as fat, so to tide them over in periods when food was less available. *
Similarly, we can divide today’s population into two groups when it comes to sugars: those who can metabolize carbohydrates normally (termed insulin-sensitive), and those who cannot (insulin-resistant). Those who cannot generally have difficulty using fat as an energy source, so they are more likely to store any excess fat calories in their fat cells. The toxic effects of this excess stored fat reduces the capacity of the muscles and liver to utilize glucose from the bloodstream, resulting in excess insulin production from the pancreas in an attempt to drive the glucose into the muscles and liver. This is especially prevalent after eating refined carbohydrates. Ultimately, this toxic glucose-fueled environment can lead to either pancreatic exhaustion or the liver and muscles become completely resistant to the action of insulin. Either way, we’re on the road straight to diabetes-ville.
Which is something we’ve pretty much known for almost 100 years. As long ago as the early 20th century, we had a pretty good idea that refined sugar led to increased insulin production, and it was this that led to higher incidences of diabetes. Canadian medical scientist Frederick Banting shared the 1923 Nobel Prize for the discovery of insulin and its effect on diabetes (by the way, Sir Frederick was a cousin of British undertaker William Banting - perhaps the first to expand on the virtues of the low-carb diet via a series of letters and entries into his journal; and the pre-cursor to low carb diets decades later, beginning with Dr Robert Atkins. Banting’s experimentations were prescribed by his surgeon, Dr Harley Street. In 1861!!).
The culprit is insulin. Always has been. Insulin is released in proportion to the rate at which glucose enters the bloodstream. Carbohydrates - especially simple carbohydrates - raise insulin levels at a much greater rate than do fat and protein. The faster insulin is raised, and the longer it stays elevated, the more, and the longer, we crave sugar. Avoid sugars - especially simple sugars, and this hormonal cascade is avoided. SO what’s the problem? Well - here’s where our addiction problem comes in...
So how is sugar addictive? Is there evidence for this?
Most people define addiction based on three criteria: desire, tolerance, and withdrawal. We need to want something for it become addictive. Tolerance implies the more you eat, the more you want to eat; and withdrawal is the tendency to feel terrible when you can't get your 'fix.'
Any of this sound familiar?
I know this is the pattern I personally go through whenever I slide down the sugary slope.
Addiction is related to the actions of two chemicals: serotonin and dopamine. A study performed by McBride proved that alcohol elicits a response from both of these neurotransmitters and are correlated with addictive behavior (McBride, 1991). A study done by Gessa showed that marijuana elicits a response from cannabinoids, our neurotransmitters that control cravings, and that these cannabinoids regulate mesolimbic dopamine (Gessa, 1997). Cigarettes have also been proven to elicit a response of serotonin and dopamine (Staley, 2001).
So how does this apply to food? Sugar also elicits a response from both serotonin and dopamine. Carbohydrate consumption - acting via insulin secretion and the ‘plasma tryptophan ratio’ - increases serotonin release; while protein intake lacks this effect (Wurtman, 1995). A 2008 study also showed that sugar elicits a response from dopamine in much the same way as cannabinoids (Avena, 2008). Because serotonin release is involved in functions such as sleep onset, pain sensitivity, blood pressure regulation, and control of the mood, many people overeat carbohydrates - particularly those also rich in salt and/or fat - such as potato chips, candy bars, and pastries. Researchers in 2011 showed that brain images of those addicted to drugs were strikingly similar to those who were constantly over-eating (Gold, 2011). Noble (1994) showed that obese individuals had the same dopamine gene markers as alcoholics and drug addicts.
When the brain "is excessively activated by sweet food or powerful drugs," says Bartley Hoebel of Princeton, "it can lead to abuse and even addiction. When this system is under-active, signs of depression ensue." (from Good Calories, Bad Calories - Gary Taubes)
So,with an understanding of the potential addictive properties of carbohydrates, along with the plethora of positive low-carb research over the years - beginning with William Banting, continuing through various researchers and nutritionists throughout the years up until the present day successes of the low-carb Atkins Diet, the Zone, and South Beach Diet, etc., why is it people are still fat? That’s always been my question.
We know this. Carbs. Make. People. Fat. Don’t we?
|USDA Food Pyramid|
Maybe I’m being presumptuous. Maybe. Being in this industry, I’m privy to this information. I’ve read the studies. I own the books. I’ve experimented on myself often. Problem is, most people don’t, and they don’t get much help. Fooled by ridiculous high-carb, low-fat recommendations by their governments (such as the USDA’s ‘food pyramid’, which was the US Government’s official recommendation guide for meals for 20 years, starting in 1992), and tricked by the even more ridiculous claims made by the food industry (for more information on this, check out David Kessler's excellent book, The End of Overeating - where he reveals the depths to which food industry scientists have gone to determine the exact amounts of salt, fat and sugar to layer food products with so that they will become as addictive as possible), is it any wonder why the issues continue.
The sad thing is that this has been this way for a while; it is no better today than it was in the early 60s, when Yale biochemist Robert Kemp wrote: “This is undoubtedly a battle for the mind where unfortunately the patient is completely unsettled by the confusion of advice offered from both professional and lay sources.” This was 50 years ago!
So perhaps ignorance can be blamed for much of the obesity problem. But what about those who are not? Those who know that the way to lose and maintain lost weight is to reduce carbohydrate consumption? Those who have tried a number low-carb diets? And failed. Or even those who have worked with trainers and coaches, who have put them on plans incorporating all the latest research on fat-loss? And still failed.
Why is it so seemingly difficult to stick to a plan?
And is there anything we can do about it?
Maybe because with sugar, excess is the norm; the more sugar there is in our foods, the more we want. The more we want, the more the food industry provides. The more they provide, the more we buy. The more we buy, the more the food industry spins the research to keep us spending. It’s a ball that is nigh on impossible to stop once it gets rolling.
The important thing is that people don’t just throw up their hands in frustration, and give up; blaming their ‘fat genes’, or citing lack of time to exercise. In part four, we’ll explore some options on how to slow down the sugar momentum, some ways we can actually change our genes, and some strategies to avoid the sugar addiction altogether.
*As an aside, Dr Paul Jaminet, author of Perfect Health Diet, has an alternative view: he proposes that our sugar cravings are actually not sugar cravings at all, but fatty meat cravings. He suggests in our paleolithic environment - with plenty of tubers and the occasional not-so sweet fruits - our sweet teeth drove us to eat calorie-dense, nutrient-rich fatty meat!