Obesity and diabetes: The gene factor.
Using careful definitions and measurements of body fatness, Professor Lesley Campbell and Dr Arthur Jenkins have shown that obesity that runs in families of people with type 2 diabetes is due to a large number of rare variants in many different genes. Their study was published in PLOS ONE.
Professor Lesley Campbell
Over the past 25 years, Campbell’s research has looked at people who are genetically at risk of developing type 2 diabetes and are overweight or obese before they get diabetes. Genes, she stresses, bring out underlying predispositions and there are fairly predictable interactions between genes and environment. She explains: ‘The reason we see so many people getting fat is that they carry strong hunger genes while the environment is maxed; it’s an obesogenic environment that rewards eating. People no longer have to go fishing, or hunting and gathering in order to eat. They just go to McDonald’s, or KFC, or the freezer. The point is that people don’t have to expend any energy to get an abundance of food, often high in fat or sugar. We have shown in previous studies that people with diabetes in the family tend to be hungry more often, are able to eat more at a sitting, and will generally opt to eat high calorie foods. This does not mean they are greedy, it just means that their bodies are genetically driven to eat more. The same genes would serve these people well in times of food scarcity or famine. They would survive, while their leaner neighbours would perish.’
Obesity and diabetes: is the association as causal as we think asks Prof Garry Egger?
‘The statistic that approximately 70–80 per cent of type 2 diabetes patients are overweight or obese led to the conclusion that there is a causal relationship between obesity and diabetes. However, the lock and key conclusions regarding the causality of diabetes are becoming questionable. It seems to be more complex than obesity alone, potentially influenced by a range of lifestyle factors. While the following facts are not conclusions in themselves, they imply that being overweight is not the sole cause of type 2 diabetes.
- Approximately 1 in 3 people with obesity have consistently shown to not have any risk factors for the dysmetabolism needed for diabetes.
- Approximately 1 in 4 people with a healthy body weight display all the metabolic risks for diabetes, risks that would be typically expected in individuals with obesity.
- According to the “obesity paradox”, overweight individuals are less susceptible to mortality from type 2 diabetes and other metabolic ailments than lean individuals.
- A better understanding of adipocyte (‘fat cell’) physiology implies that triglyceride storage in adipocytes is healthy until excessive energy abnormally ‘outpours’ into the liver, muscles and blood.
Extending upon the final point, in the body, fat storage increases via two processes, the first being hypertrophy, meaning expansion within the adipocyte, and the second being hyperplasia, in which new adipocytes are formed due to established cells being “full”. Undetermined genetic factors seem to reduce adipocyte hypertrophy. Once this hypertrophy has reached its limit, ectopic fat (for instance, as in fatty liver) occurs due to the “outpour”. Ectopic fat is toxic and results in oxidative stress and metaflammation, a low-grade form of systemic inflammation that correlates with a metabolic cascade resulting in insulin resistance.
What does this imply for diabetes management? There is the likelihood that weight loss is less of a priority than improving eating habits, exercising and sleeping more and managing stress. Mounting evidence is finding exercise to be one of the most effective individual changes, with recent research demonstrating that high intensity resistance exercise decrease IR-associated visceral fat.’
– Prof Garry Egger was a keynote speaker at the AustralAsian Academy of Anti-Ageing Medicine Conferenceheld in Melbourne, 24-25 August.
Dementia risk and BGLs.
Higher blood glucose levels are associated with higher dementia risk, even among people who do not have diabetes according to a study published in the New England Journal of Medicine. Reporting on more than 2,000 Group Health patients age 65 and older in the Adult Changes in Thought (ACT) study, the researchers found that blood glucose levels averaged over a five-year period were associated with rising risks for developing dementia. ‘The most interesting finding was that every incrementally higher glucose level was associated with a higher risk of dementia in people who did not have diabetes,’ said lead author Dr Paul K. Crane.
Organic labels and ‘health halo’ bias.
A study by Cornell University’s Food and Brand Lab researchers shows that an organic label can influence perceptions of taste, calories and value. The researchers recruited 115 people to take part in the study. Participants were asked to rate the taste and caloric content of 2 yoghurts, 2 cookies and 2 potato chip portions and say how much they would be willing to pay for them. One item from each food pair was labelled ‘organic’, while the other was labelled ‘regular’. In fact all were organic and the products were identical. What were the findings? The participants estimated the cookies and yoghurt had significantly fewer calories when labelled ‘organic’ and were willing to pay up to 23.4% more for them. They also reported that the ‘organic’ yogurt tasted ‘lower in fat’ and the ‘organic’ cookies and chips were more nutritious. In addition, ‘organic’, chips were perceived as being more appetizing and organic yogurt more flavourful. ‘Regular’ cookies however were reported to taste better than ‘organic’ – is this because people often believe healthy foods are not tasty?