Adolescent Obesity Kills Middle-Aged Adults

Yes, there's a childhood and adolescent obesity epidemic out there. The word on the street now is that "this is the first generation of kids, who will not outlive their parents".

But is this really true? Where is the data showing that childhood obesity is really a risk factor for early death?

This question is now answered by perhaps the largest study on this issue to date published by Tone Bjørge and colleagues from the University of Bergen, Norway, in the American Journal of Epidemiology.

Bjørge and colleagues studied the relationship between BMI (measured height and weight) and mortality in 227,000 adolescents (aged 14-19 years) recruited in Norwegian health surveys in 1963-1975. During follow-up (8 million person-years), 9,650 deaths were observed. Cause-specific mortality was compared among individuals whose baseline BMI was below the 25th percentile, between the 75th and 84th percentiles, and above the 85th percentile in a US reference population with that of individuals whose BMI was between the 25th and 75th percentiles.

Risk of death from endocrine, nutritional, and metabolic diseases and from circulatory system diseases was increased in the two highest BMI categories for both sexes. Relative risks of ischemic heart disease death were 2.9 for males and 3.7 for females in the highest BMI category compared with the reference. There was also increased risk of death from colon cancer (males: 2.1; females: 2.0), respiratory system diseases (males: 2.7; females: 2.5), and sudden death (males: 2.2; females: 2.7).

The authors conclude that adolescent obesity is related to increased mortality in middle age from several important causes.

Clearly not a good sign for what awaits our sons and daughters unless we get a hold on the obesity crisis.

AMS
Edmonton, Alberta

Sarcopenic Obesity and Cancer

We know now (although many still do not fully appreciate this) that obesity is a major risk factor for cancers. On the other hand in patients with many chronic diseases, larger patients tend to do better and live longer (the obesity survival paradox).

Last week researchers from the University of Alberta published a study in The Lancet Oncology, that adds another level of complexity to the relationship between obesity and cancer survival. Clarisse MirandaPrado together with other researchers from the UofA, including cancer cachexia researchers Vickie Baracos, studied 2115 patients with solid tumours of the respiratory or gastrointestinal tract, 325 (15%) of who were classified as obese (body-mass index [BMI] >/=30).

With the help of CT images, the researchers found that obese patients had a wide range of muscle mass, with 15% of analysed obese patients meeting criteria for "sarcopenic" obesity (sarcopenia is the medical term for low-muscle mass). By definition, sarcopenic obese patients have more body fat and less lean body mass than non-sarcopenic patients of similar weight.

Not only was sarcopenic obesity associated with poorer functional status compared with non-sarcopenic obese patients but these patients also had a 4-fold hgher risk of dying.

Incidentally, the researchers also used their data to calculate that using conventional dosing criteria for cytotoxic chemotherapeutic drugs, sarcopenic obese patients may be overdosed with a greater likelihood of toxicity.

Overall this study shows that obesity is never just obesity and that BMI in the clinic is a fairly useless concept (a point that I have argued before) and that without proper assessments of body composition rational management of large patients is just not possible.

A patient's size alone proves little in term of health or disease - remember, weight alone is a rather poor measure of health.

AMS
Edmonton, Alberta

Obesity and Prostate Cancer

Looks like this week is about obesity and men's health. So after blogging about male self-esteem and erectile dysfunction, what about obesity and risk for prostate cancer?

Well, after a quick search of the literature, I can happily state that the data on this is pretty inconsistent.

Probably the best study, a prospective cohort study in 34,754 men residing in Washington State (aged 50-76 years at baseline) studied by Alyson Littman and colleagues from the Fred Hutchinson Cancer Research Center, Seattle, WA, published in the American Journal of Epidemiology, succeeded in confusing me more than providing any definitive answers.

Thus, while on one hand obese men had a reduced risk of nonaggressive disease, overweight (but not obese) men, had an increased risk of aggressive disease. Body mass index of >25 at age 18 years was associated with increased risk of aggressive prostate cancer; obesity at ages 30 and 45, but not 18, years was associated with reduced risk of nonaggressive prostate cancer.

I can only concur with the authors, who conclude that this study demonstrates the complexity of prostate cancer epidemiology and the importance of examining risk factors by tumor characteristics.

So is obesity a significant risk factor for prostate cancer? I guess the answer is "depends".

AMS
Edmonton, Alberta

Does Surviving Cancer Lead to Weight Gain?

Yesterday's big news was the study by Kerry Courneya, professor and Canada Research Chair in Physical Activity and Cancer at the University of Alberta, published in CANCER.

I am not going to repeat the findings or the data here because this was nicely summarized by Sharon Kirkey from Canwest News Service in the Edmonton Journal.

The bottom line is that cancer survivors are apparently not exercising more or eating healthier than everyone else, and are therefore at least as, if not even more, likely to develop obesity than the average Canadian.

This is particularly true for survivors of breast and colon cancer, which are particularly likely to recur with lack of physical activity, unhealthy eating and weight gain.

The dramatic impact of weight on cancer risk is perhaps best demonstrated by the observation that obesity surgery, which on average reduces body weight by 25%, results in an almost 60% reduction in cancer mortality! (see Adams et al. for an example of such a study).

I guess it just goes to show that cancer survivors are no less susceptible to the consequences of our obesogenic environment, which certainly does not make weight control easy, even at the best of times.

That is of course, unless there is something special about surviving cancer that makes you more likely to gain weight - an interesting hypothesis pursued by other researchers here at the University of Alberta.

I can think of a number of reasons why surviving cancer could predispose to weight gain: "catch-up" fat, depression, "post-traumatic" stress, anxiety, susbtance abuse, "overfeeding", immobility, medications, and perhaps a few others.

Whatever the reasons, it looks like we may now need intervention programs to specifically address weight gain and obesity in cancer survivors?

For one, educating cancer survivors about the links between excess weight and cancer would be a start.

My sense is that most people still don't fully appreciate the close link between obesity and cancer - all the more reason to promote healthy eating and active living for all.

Obesity prevention (and treatment?) may well turn out to be the most effective cancer prevention strategy (short of smoking cessation) - looks like a whole new field for bariatric health professionals?

I guess we'd call them Bariatric Oncologists?

AMS
Edmonton, Alberta