Thursday, February 26, 2009

Reduced Calorie Diet & Body Mass Index

Reduced-calorie diets seem to help diminish body weight. Sacks and others (2009) report in the New England Journal of Medicine (360:859-873) that eating reduced-calorie meals with differing allotments of carbohydrates, fats, and proteins helped 645 overweight adult men and women, who stringently dieted for two years, lose on average 4 kg (roughly 9 pounds). The findings caught the attention of the national media. Tara Parker-Pope filed a report on them in her column Well for The New York Times already yesterday evening. CNN's Madison Park posted a detailed report about the study today.

The participants of the study conducted at Harvard University and Louisiana State University had body mass indexes between 25 to 40. Body mass index (BMI) was calculated dividing the weight in kilograms by the square of the height in meters (see attached converter). Diets low and high in fat and protein were personalized to provide 750 kcal less per day than the baseline expenditure determined for each person.

Statistical analysis showed that all diets tested diminished body weight noticeably, though not statistically significantly. The various types of diet did not differ significantly in the diminution of body weight. However, encouragement with counseling reinforced weight loss. More persistent encouragement, in particular the addition of physical activity regimens, could have enhanced the observed small differences in effect.

Using the converter below, you may convert your body weight [pounds] and body height [inches] into metric dimensions according to the Système International by entering the appropriate values in the blue boxes and clicking on the green boxes. If you use metric measures, just enter your data in the green boxes. Subsequently, clicking on the body mass index button calculates this value.

[in] : [cm]:
[lbs]: [kg] :

© You may donate for further development through PayPalhere. The converter is available for MySpace users under the App name YourBMItoday.

  • Keith Devlin discusses ten reasons why BMI may constitute an unrealistic indicator of obesity in an segment broadcast on yesterday's Weekend Edition of National Public Radio (05/07/09).
  • According to Will Dunam's post on Reuters dated May 3, 2009, reduced-calorie diets promote longevity possibly through the expression of pha-4 related genes, the products of which are  involved in the balancing of blood sugar (07/14/09).
  • Nicholas Wade reports in his post for The New York Times, dated Jul. 9, 2008, on results of a longitudinal research study with rhesus monkeys (Coleman and others, 2009), suggesting that reduced-calorie dieting extends average lifespan  (07/16/09).
  • Alex Witchel's article for The New York Times posted Oct. 6, 2009, describes the preliminary results of the first scientifically controlled studies using restricted diets on participants of normal weight. The imposed dietary regimens may be difficult to adhere to, once we are left to our own whim. The studies have not advanced to that point yet. Perhaps, the most insightful result to date is the notion that keeping track of our food intake in a conscientious effort helps (10/09/09).
  • The discussion below gave me pause. It would be great, if this example of weight control were the result of pure self discipline (10/16/09):
  • On Mar. 4, 2010, Maggie Fox posted a report with the title "Your best diet? It might be in your genes" on a recent study uncovering variations in the genes ADRB2, FABP2, and PPARG that may play a crucial role in the efficacy of diet types. The products of these genes are proteins that influence the secretion of insulin from the pancreas (ADRB2), facilitate fatty acid metabolism, (FABP2), and regulate fatty acid storage and glucose metabolism (PPARG). The study was presented at the American Heart Association's Joint Conference - 50th Cardiovascular Disease Epidemiology and Prevention - and - Nutrition, Physical Activity and Metabolism - 2010, held in San Francisco last week (Dopler Nelson and others, 2010). The results of the study are based on the examination of 140 overweight women. Four diets were randomly assigned to the participants: Atkins (low in carbohydrates), LEARN (extremely low in fat), Ornish (low in fat), and Zone (balanced). Personal genetic profiles were analyzed in roughly 100 participants, using an assay available from Interleukin Genetics Inc. Over one year, participants with the diet matching their genetic profile lost twice the body weight (5.3 precent) than the participants on mismatched diets (2.3 percent). Note that people on restricted calorie diets lose about 10 percent in the same time span (03/07/10).
  • Our body mass index is supposed to range between 18.5 and 24.9 to keep us healthy. Kathrine Rosman provides some interesting facts for the benefits of a little more weight in her Wall Street Journal post with the title "A Case for Those Extra 10 Pounds" two days ago. A few more pounds seem okay, as long as they are not visceral. That's my snag (04/29/10)!
  • According to Gautam Naik's post entitled "Gene Curtails Alzheimer's in Mice" on The Wall Street Journal today, Guarente and others (2010) provide evidence that sirtuin 1, the product of the gene SIRT1, the expression of which is induced by reduced-calorie diets, helps prevent the formation of amyloid plaques and memory loss in a mouse model for inheritable Alzheimer's disease (AD). AD mice that had additional SIRT1 inserted into their genome showed the positive results, wheras AD mice that had SIRT1 knocked out off their genome deteriorated extraordinarily fast (07/22/10).
  • Rick Wilking provides as with a gallery of slides published online on Reuters yesterday with the title "Big U.S." documenting obesity in America. We may wish to consult the BMI table on slide #33. As long as our BMI is in the white part of the table, we are fine (10/09/10).
  • Bruce Grierson informs us in his astounding essay with the title "The Incredibly Flying Nonagenarian" published online in The New York Times today about the achievements of athletes at advanced age, the physiological and genetic basis underlying such incredible performance, and the beneficial effects of physical fitness. Persistent physical exercise routines may slow aging, because the more efficient use of calories may stem the degradation of genes involved in tissue regeneration, enhancing and preserving our physical potential. Watch Olga Kotelko at age 91 (11/25/10):
  • According to this Reuters chart with the title "Obesity" published online Dec. 9, 2010, BMI statistics suggest that Italians and French are less overweight than U.S. Americans and Germans. Must be the food (12/16/10)!
  • Remaining focused on a regimen of diet and exercise over the long haul is difficult for most. Applications like the SlimKicker may provide helpful support in a playful way (04/20/12).
  • Excess body weight has reached national proportions. According to Linda Wertheimer's interview with Dr. Ian Roberts at the London School of Hygiene and Tropical Medicine with the title "Study: Fat People Burden Earth's Resources" aired on National Public Radio's Morning Edition today, the U.S. is adding the equivalent of more than one billion people in overweight to the Earth's population (06/20/2012).
  • According to the latest results of a long-term study with rhesus monkeys conducted by the US National Institute of Aging (NIA) intramural program (Mattison and others, 2012), a reduced calorie diet did not extend life. The difference in outcome compared with the study of Colman and others (2009) may lie in study design. The control monkeys in that study were allowed to indulge in as much food as they could eat, whereas the food supply for the control monkeys in the NIA study was limited (09/29/2012). 

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