Showing posts with label calorie restriction. Show all posts
Showing posts with label calorie restriction. Show all posts

Saturday, September 29, 2012

CALORIE RESTRICTED DIETS-LONGEVITY CLAIMS UNDER CLOUD

Who does not want to look lean and strong and besides the cosmetic value a good personality radiates, lean body mass is a scientifically proven route to keep good health. While following a strictly balanced daily diet is the surest way to good health, as in many cases of human life, such disciplined eating is more easily talked about rather than being followed! This human weakness for good tasting food with irresistible  flavor and texture credentials is being exploited by many industry players with utter disdain for consumer well being. There are a number of preachers for weight reduction like Atkins, South Beach, Portion Planners etc and billions of dollars of business is riding on this area of health management. How far they are able to substitute human determination and self exercised will power is a mute point as long as there are willing consumers to believe in such unnatural means of achieving weight reduction as quickly as possible.

One of the earliest theories which was floated to achieve longevity and good health was practicing a diet low in calories, much lower than what is recommended, which is supposed to control the body metabolism for preventing fat accumulation responsible for weight increase over a period of time. It was in 1934 that Restricted Calorie (CR) diet theory sprouted in Cornell University, USA based on demonstrable effect of such a diet in extending the life span 100% in rats under laboratory conditions. Since then hundreds of studies in different parts of the world did show that reducing calories in daily diets to the extent of 10-25% could prevent undue weight gain in many animal models. It has been claimed by these studies that such diets are successful in controlling blood pressure, fasting glucose, fasting insulin, BMI, body fat percentage, C-reactive proteins, carotid IMT, Platelet derived growth factor AB and boosting memory status among the animals studied.

An indication about calorie restriction effect was obtained during early studies with yeast, fish, rodents and dogs and such CR diet regimen without causing micro nutrient deficiency was shown to increase both median and maximum life span among the animals studied. Though these results were taken as proof of the scientific basis for confirming the effectiveness of CR diets and promoted for human beings also without adequate mammalian or human studies, there has never been a "sufficiently powered" long term randomized clinical trials of CR in humans to confirm or deny its efficacy in achieving what has been seen in animals. The longest running scientific study of CR in primates has been undertaken in University of Wisconsin and is going on since 1989 without coming to any definitive conclusions regarding the success of CR diet universally.    

CR diet intervention and its usefulness in prolonging life became a focal point of attention recently when National Institute of Health came out with some startling news based on studies in its Institute of Aging (NIA) that CR diets might not be as effective as being claimed during the last several years. After 25 years of observations, it came out that rhesus monkeys fed only a lower-calorie diet lived no longer than their rhesus mates who ate a little more and weighed a little more. This is in stark contrast to what was reported earlier from a slightly different study led by investigators in Wisconsin. which found healthier life for their group of starving monkeys. The NIA study was of a blow to many enthusiasts who whole heartedly welcomed the idea proving that "less equals more when it comes to eating"!. Unfortunately this finding may have the consequences of nullifying the mindset among many consumers that self restraint, continence, and composure in controlling one's appetite pays off in the long run. But the jury is still out on this issue and a closer look at the results may suggest it's not time to indulge in foods ad libitum just yet.

A critical question that may haunt weight watchers and "long life' lovers is whether the new information will allow one to eat a bad, sugary diet, provided too much of it is not eaten. The simple fact is that if one eats more of such foods without control, death is likely to visit sooner than later!. However if good food in terms of balanced nutrition with low sugar, salt and fat using more of whole grains, it may not matter even if more is eaten. In terms of longevity whether CR diet or rich diet, life span may be same though those in the latter category, eating more will still live long albeit weighed down by diabetes and other medical conditions. At least that is the current take on this interesting issue!

V.H.POTTY
http://vhpotty.blogspot.com/
http://foodtechupdates.blogspot.com

Monday, August 3, 2009

PRECIOUS 'LIFE'-WANT TO 'HANG ON'?



Keeping one's weight under control is considered to be the most practical step in prolonging the life unrestricted by onset of life-threatening health disorders. BMI and Obesity find mention in practically all references touching on the subject of longevity. Going beyond the desired goal of weight control, man is becoming more ambitious or rather 'greedy' to cling on to the Mother Earth, if not permanently but at least for a few years more than what is expected. Use of appetite suppressant by over weight people, to reduce calorie intake and thus control body weight is now being tried to prolong life amongst, other wise, normal healthy persons. The clue is provided by the findings by many studies that in rodents and some primates deliberate restriction of calorie intake enables them to extend their life span by as much as 40%!.

'Calorie restriction' (CR), according to experts, is a strategy for 'extending' healthy life, evolved based on 20 years of studies on animals which gained life extension, as much as 40%. CR is claimed to confer other benefits that include lowering the risks of most degenerative conditions of aging, reducing other risks like DNA damage, enhanced cleaning up of cells, enhancing DNA repair, protecting against aging of the heart, slowing down the deterioration in the immune system, restraining the development of Alzheimer's disease, arresting stem cell decline, reducing inflammation and checking muscle degeneration. Yeasts, fish, rodents,dogs and primates have all achieved extended life span to varying degrees, though limited studies reported on humans are still inconclusive. One of the examples cited to support the effectiveness of CR concept is the population in Okinawa, Japan which boasts of high numbers of long surviving people who habitually consume only 80% of daily food requirement as a part of their traditional eating practice.

The mechanism of slowing aging through CR is not well understood but some believe that it decreases the insulin levels thereby "upregulating autophagy". Contrary to this, studies using Sirt1 protein for longevity, scientists found the insulin levels in their studies increased significantly creating complications while Klotho protein, another longevity aid, produced lesser insulin creating diabetic like conditions. Unless the precise mechanisms of various anti-aging approaches are known, wide scale practice of such systems is ruled out. But calorie restriction is still an option, if not for longer life span but at least for a more healthier life on which there is a near unanimity amongst the scientists. Perceptions differs only as to how much restriction of calorie intake must be practiced to get maximum benefits from such a regime in to day's world where over-weight and obesity are endemic..

Antagonists of calorie restriction approach dwell on the fact that results of animal studies cannot be extrapolated on humans and the benefits of CR are far less than what is claimed. While rodents achieved 40% life span extension on CR, humans, it is claimed, can never expect to get more than 7% increase in life expectancy at practical levels of CR. Even in animal studies many aberrations were noticed such as undesirable changes in behavioral pattern, emission of foul body odors, irrational irritability, greatly reduced fertility, unbearable hunger pangs and greatly lowered energy levels incapable of carrying many normal activities. Added to this confusion some studies report that CR is effective in slowing down aging only in obese mice and normal healthy ones do not benefit at all.

CR to be effective must be practiced when young and people at the fag end of their life cannot get benefit through this diet restriction technique. If that is so it raises many questions that are legal, moral and ethical. Which mother will agree to restrict food to her child during the early stages of growth? Is it morally right to deny foods to the children when they are growing fast during the childhood? Will the practice pass legal test regarding the rights of a child before reaching adulthood? Will some one sacrifice one's quality of life to get a few extra years on this planet? Will it not be better to live healthy for some time than living with diabetes for long time? Industry has to be weary about entering into such a field with future repercussions about the possible impact on society.

V.H.POTTY
http://vhpotty.blogspot.com/