This article presents a broad overview of calorie restriction as an intervention to increase lifespan. Although the article reminds readers that the potential for longevity benefits in humans is not proven, the tone of the article is that we are well on the way to that proof, which is not the case. This story reports on the recent randomized controlled trial of calorie restriction in humans which showed that during a period of weight loss, there was improvement in some measurements suggesting the potential for extended lifespan. The article mentioned a study which found that people selected on the basis of self-imposed calorie restriction have been found to have better cardiovascular profiles compared to similarly-aged individuals who ate a more typical number of calories each day. Calorie restriction was presented as a difficult proposition and that there are ongoing efforts to determine whether it is possible to get the same benefits through smaller reductions in calories coupled with exercise, consumption of some undetermined food assortment or with the use of a drug to cut appetite. The article summarizes what is currently known about calorie restriction as a way to increase human lifepan, but the current gaps in knowledge were presented less prominently. The story says that this is “a quickly evolving concept that could prove to be a mini fountain of youth.” That “quickly evolving” view of science, promoting an expectation of even a “mini fountain of youth” does not serve public understanding.
There was no comparison of the costs of eating a lower calorie, though nutritionally adequate diet as compared to a standard Western diet. Higher quality diets can be more expensive.
The benefits observed in humans (i.e. from the randomized controlled trial – improvements in insulin levels, decreased body temperature, and less DNA damage; the case controlled study – more elastic hearts, lower levels of inflammatory cytokines) were mentioned without indicating the magnitude of the difference between experimental groups or whether the differences were statistically significant. Readers need help figuring out how big the potential benefit may be.
The story mentioned unwanted side effects of calorie restriction: low blood pressure, reduced sex drive, menstrual irregularities, infertility, bone thinning, cold sensitivity, lose of strength, slower wound healing and various psychological conditions.
Without indicating the types of experimental designs the studies used, the story presents results of one preliminary randomized controlled trial and one small case-controlled study in a framework of results from animal experiments. Some results from one of the on-going experiments with non-human primates were presented, without indicating their lack of stastical significance at this time.
References to a “fountain of youth” set the wrong tone for this story, akin to labeling aging as a disease. Two statements from one researcher beg an evidence-based review. “While the finding does not guarantee they will live to 100, their life expectancy is higher” is followed by “Their risk of developing a myocardial infarction (heart attack) or stroke was close to zero.” This article exaggerates the implications of changes in human and animal physiology in the laboratory, and short-term experiments on longevity.
The story mentioned several on-going human studies, one of the primate studies and a nod to the numerous rodent studies of calorie restriction. Investigators involved in calorie restriction work were quoted and several peer reviewed articles on this topic were mentioned. However, there was no discussion of potential conflicts of interest of any of these sources.
The variety of species in which calorie restriction has increased lifespan was mentioned as well as the caveat that a comparable longevity benefit remains to be proven for humans. There are no known treatments that reliably and reproducibly increasing human longevity.
The story reports that “a group of researchers found that depriving overweight, but non-obese, people of about 25% of their normal calories, while still having them eat nutritionally balanced diets, led to physiological changes associated with increased longevity.” But it didn’t explicitly mention people restricting calories on their own, i.e. not as part of an experimental protocol. No specific information was provided on the diet or where information on it might be available.
The story discusses the latest results of calorie restriction to combat aging in the context of previously published studies and repeatedly refers to the preliminary nature of the evidence.
No obvious reliance on a press release.