Monday, September 24, 2012

The Latest On The Glycemic Index

David Ludwig of the New Balance Foundation Obesity Prevention Center and colleagues recently published a study in the Journal of the American Medical Association.  The study compared low-fat, low-carb, and low-glycemic diets.  While the low-carb diets prevailed and the low-fat diet ended up with the bronze, the low-glycemic was the easiest to follow for participants.  
The glycemic index is a tool used to measure how fast a food is digested.  It's been useful for dieters because it increases satiety.  The higher end of the glycemic index is packed with processed foods while lower glycemic foods are based on whole grains, fruits, vegetables, and legumes...basically the perimeter of the grocery store this taking meat and dairy products into the equation.  On the downside, the glycemic index can be hard to follow or understand between dieters worrying about calories, fat, protein throwing in meal combinations and digestion might be a little too much for some people.  
The last piece of the study included participants after the study, those that kept the weight off had included 60-90 minutes of exercise per day.  
Read the whole article from NPR here.

Bacteria And Weight Loss: Beyond Your Morning Yogurt

New evidence suggest that bacteria can play a role in weight gain.  Certain bacteria may activate enzymes that increase fat storage and decrease hormones that control appetite explains a French study lead by Frank Duca of the National Institute for Agricultural Research in Jouy-en-Josas.  Obese people have different gut bacteria than thinner people do.  The researchers hope to one day be able to shift a person's mix of gastrointestinal bacteria with pre/probiotics and diet changes to help with weight loss.

Additional reading:

Gina is a SCAN dietitian and can be found blogging at

Monday, September 17, 2012

Dads And Nutrition

We get a lot of things from our parents.  Up until recently, scientists and health experts put a lot of stress on expectant mothers, take folic acid during child bearing years, watch your calcium, keep your weight in a healthy range, don't smoke.  It seemed like the male counterpart could partake in whatever desires they wished.  New research in epigenetics from an article in The New York Times discusses the quality of a man's sperm in reproduction.

"Doctors have been telling men for years that smoking, drinking and recreational drugs can lower the quality of their sperm. What doctors should probably add is that the health of unborn children can be affected by what and how much men eat; the toxins they absorb; the traumas they endure; their poverty or powerlessness; and their age at the time of conception. In other words, what a man needs to know is that his life experience leaves biological traces on his children. Even more astonishingly, those children may pass those traces along to their children."

Christina Hultman of the Karolinska Institute of Sweden published a meta-analysis of a population study of a million people in 2011.  It concluded that men who had children over the age of 50 were 2.2 times more susceptible to have children with autism than men who were 29, this had also factored out mothers' ages and known risk factors for the condition.  By the age of 55, the risk of autism increases to 4.4 times.

"Aging, though, is only one of the vicissitudes of life that assault a man’s reproductive vitality. Think of epigenetics as having ushered in a new age of sexual equality, in which both sexes have to worry about threats to which women once felt uniquely exposed."

Read the full article from The New York Times here.

Sunday, September 9, 2012

Hydration & Sports Drinks: The Science Vs. Selling It

In the July issue of the British Medical Journal provided a very insightful look into the science of sports drinks, marketing, and our new fascination with dehydration, which the journal coins the term "the disease of exercise".  You may read the full article here.

During the road running and marathon boom of the 1970s, drinking fluids during exercise was cautioned against as it was thought to slow the athlete down.

Over the years, scientists have been sponsored by companies to develop an area of science entirely for hydration.  This has funneled down entirely to every day fluid consumption.

In the 1960s, Robert Cade, a renal physician, developed a drink with sugar, water, salt, and monosodium phosphate which was mixed with some lemon juice to become Gatorade.

On the marketing side, CocaCola (who acquired Gatorade in the early 2000s) and GlaxoSmithKline (who have their own line of sports drinks) have kept the buzz around sports drinks as a staple.

"The key behind the meteoric rise in consumption of sports drinks lies in the coupling of science with creative marketing. What started life as a mixture of simple kitchen food stuffs has become an “essential piece of sporting equipment."

Outside of hydration, studies have been shown that consumption of glucose with electrolytes can impact longer duration exercises exceeding an hour with also intensity being taking into account.  The marathon 
runner during a 12 mile tempo run has different needs than the group aerobics class participant.

Athletes and avid exercisers alike are blitzed with conflicting advice about hydration (drink x number of 8 oz glasses of water...weigh yourself after activity and drink a pint of water for every pound loss, make sure your urine is a pale yellow).

Another concern is hyponatremia which is a drop in sodium levels and has taken the lives of 16 marathoners and has sent 1600 to the hospital during events.  Hyponatremia is caused from drinking too much (usually water) or having a positive fluid balance.  

The industry has also been reaching out into the school system, where carbonated beverages are now bad, sports drinks have snuck into the lunch rooms, soccer fields, and other practice fields.

This young targeted audience has health care professionals concerned about weight gain and ties to obesity.  Most people overestimate their calorie burn as is while repleting with a 150-200 Calorie beverage when the probably only expended 200-300 Calories, great to maintain weight yet not for weight loss.    

The article is very detailed and covers several more areas about 'scaremongering over the effects of dehydration' (this is the British Journal) and whether the real target audience is the everyday consumer that might causally jog or do a few workout tapes.  

Food for thought: has dehydration been an issue in your practice?  What recommendations have you used in your career?