Richard Lehner

New findings published by University of Alberta researchers in a recent issue of Cell Metabolism may point to a new pharmacological target for reducing fat and blood sugar levels in blood while also positively affecting energy expenditure (at least in mice).

The research team, led by Richard Lehner (picture), showed that genetically knocking out an enzyme called TGH (triacylglycerol hydrolase), which is normally involved in helping the liver (and other tissues) process fat, not only reduces blood fat levels but also improves insulin sensitivity and glucose tolerance.

Interestingly, the animals were also better able to utilize glucose and, despite consuming significantly more energy, they displayed increased locomotor activity and consequently did not gain weight.

As always, such studies in mice must be taken with a grain of salt in that there is usually a long way to go before (if at all) these findings pan out in new treatments for humans.

On the other hand, these studies do demonstrate the potential of TGH as a therapeutic target for lowering blood lipid levels and possibly body weight through a novel pathway.

AMS
Munich, Germany

In medical school I learnt that we have four senses of taste: sweet, sour, salty, and bitter.

Several years ago a fifth sense, umami, was officially added to this list. Umami is stimulated by glutamate (as in MSG) and apparently allows us to taste protein (as in meat, sea food, or cheese).

Now, Jessica Stewart and colleagues from Deakin University in Australia show that a sixth sense, i.e. the ability to orally “sense” the fat content of foods may explain differences in fat preferences (British Journal of Nutrition).

Indeed, previous studies in animals have suggested that oral hypersensitivity to fatty acids (the building blocks of fat) are associated with decreased fat intake and body weight.

In the current study, the investigators first examined the taste thresholds for different types of fatty acids (olate, linolate, and laurate) in 31 normal weight subjects and classified them as hypo- or hypersensitive. Subjects also completed a fat ranking task using custard containing varying amounts (0, 2, 6 and 10 %) of fat.

Hypersensitive subjects reported lower energy and fat intakes, had an increased ability to rank the custards based on fat content and also had a lower BMI levels.

These data suggest that the increased ability to detect nutritional fat may result in lower energy and fat intake, which in turn may result in lower body weights.

Obviously, the idea here is that people who are less sensitive to fat are likely to need more fat in their foods to get that same level of enjoyment as people with more sensitive fat receptors. Because of fat’s high caloric content, this means that they may in the end also end up with more calories, and thus, weight gain.

I can think of a number of interesting questions that these findings may prompt:

1) Is the increased ability to taste fat genetic or are changes in fat-sensitivity determined by habitual fat intake (gustatory plasticity)?

2) Does weight loss affect people’s ability to taste fat (resulting in them searching out fattier foods when on a diet)?

3) Does going on a low fat-diet increase fat sensitivity thereby allowing people to get the same pleasure out of low-fat foods?

4) Can we develop artificial compounds that can stimulate the fat receptors thereby mimicking a higher fat content of foods (like we do with artificial sweeteners)?

Lots of interesting questions, which may not only explain why some people derive more pleasure from fatty foods than others but also open new possibilities for the food industry to manipulate the taste of foods (hopefully to our benefit).

I’d love to hear from my readers regarding their thoughts on “tasting” fat.

AMS
Edmonton, Alberta

Over the past three days, newspapers across Canada have been publishing a three-part series on obesity by CanWest’s Sharon Kirkey.

For this mini-series, Sharon spoke to many prominent and outspoken Canadian Obesity Network members including Valerie Taylor (McMaster), Eric Doucet (Ottawa), Nikolas Christou (McGill), Robert Ross (Queens), Yoni Freedhoff (Ottawa) and researchers from the US on a wide range of subjects relevant to this topic. She also interviewed a number of people who have struggled with obesity and its many physical and psychosocial consequences.

As expected, not all experts agree on every aspect of the debate and some statements are clearly more controversial than others. Nevertheless, I would certainly view the articles as a balanced and insightful view of the true causes of the obesity epidemic and the possible solutions (or rather the barriers to solutions).

For those who missed the series, here are the links:

Part 1: The exercise myth: Physical activity plays an important role in healthy living, but it’s not enough to make you lose weight.

Part 2: The trouble with food: A look at the science and psychology of overeating.

Part 3: Fighting an epidemic: A search for the solution.

While readers may criticize that many topics relevant to the obesity discussion were not mentioned (e.g. gut bacteria, genetic programing, sleep deprivation, etc.), remember, this was a three-part not a ten-part series on this topic. 

Noticeably, the same articles appeared under different headings in different papers, in some with more controversial titles than in others (I guess the local editors wanted to add their own spin to attract readers).

Although, I believe that the articles do discuss both sides of the debate on each of the topics,  I am sure that the critics will find their pet-topic under- or mis-represented.  Indeed, I am convinced that many readers, especially those with their usual grudge and bias against obese people as well as those who have all the (simple) answers, will probably be unhappy.

I can only commend the editors of these papers (and of course Sharon) for taking on this important topic and not shying away from controversy, which I know these articles will provoke.

The more open debate we have on this subject, the better.

Appreciate views from any of my readers, who have read these articles.

AMS
Edmonton, Alberta

There is no doubt that dietitians are the health professionals most often looked to for advise on weight management.

It may therefore come as a surprise to many readers that although dietitians have vast knowledge about healthy eating and the dietary management of a wide range of diseases like diabetes, kidney disease, celiac disease and many others, most dietitians interestingly do not have specific training in treating obesity (the same can sadly be also said for the vast majority of doctors, nurses, exercise physiologists, or any other health profession you can think of).

No one is more acutely aware of this lack of expertise than the dietitians themselves, especially as they are so often called upon for dietary advise by people trying to manage their weight.

As anyone working in this field quickly recognizes (and regular readers of these pages will know this by now), eating or ingestive behaviour is only one part of the energy balance equation and even there, the many socio-psycho-biological factors that determine caloric intake are anything but simple.

I am therefore particularly pleased that the Dietitians of Canada have partnered with the Canadian Obesity Network to co-host the first pan-Canadian Learning Retreat on the Principles & Practice of Interdisciplinary Obesity Management for Dietitians, that is currently being held in Winnipeg.

The aim of the retreat is of course not to teach dietitians about counseling clients on healthy eating or even about nutritive approaches to weight losst. Rather, the retreat focusses on all of the other topics that dietitians need to know about in order to fully understand and appreciate the many factors that are essential for effective obesity management.

It is therefore not surprising that there is a lot of room on the program for the discussion of topics like weight bias, psychosocial factors, mental health, neurobiology of hunger and satiety, exercise physiology, body composition, and of course medical and surgical management of obesity.

Judging by the enthusiasm of the attendees, it appears that such a learning opportunity has been long overdue and I am certainly hopeful that events like this will help ensure that patients struggling with excess weight will have an increasing number of dietitians to turn to, who have been specifically trained in obesity management.

AMS
Winnipeg, Manitoba