Dr. John Blundell

Yesterday, I had the pleasure of hosting John Blundell, at the Research in Progress seminar series at the Alberta Diabetes Institute.

Dr. Blundell is Professor of bio-psychology at the University of Leeds, UK, and is certainly one of the preeminent authorities on the bio-psychology of ingestive behaviour.

His presentation with the rather provocative title, “Will exercise make you fat?”, started with a broadside at the media, which lately has been quite active in promoting this notion.

However, as Blundell pointed out, this simplistic message is far from accurate in that the relationship between physical activity and its impact on ingestive behaviour and body weight is anything but straightforward.

For one, although short-term studies (days) do often show an increase in appetite, this is by no means regularly observed in longer-term studies (weeks).

In a paper he recently published in the Journal of Clinical Endocrinology and Metabolism, Blundell recently examined the effects of medium-term exercise on fasting and post-prandial levels of appetite-related hormones and subjective appetite sensations in overweight and obese individuals.

The study included 22 sedentary individuals who took part in a 12-wk supervised exercise programme (five times per week, 75% maximal heart rate) and were requested not to change their food intake during the study.

Not only did exercise result in a significant, albeit modest (~3 Kg), reduction in body weight and fasting insulin and an increase in ghrelin plasma levels but also in a reduction in fasting hunger sensations.

A significant reduction in postprandial insulin plasma levels and a tendency toward an increase in the delayed release of glucagon-like peptide-1 (90-180 min) and a greater suppression of postprandial ghrelin.

Thus, although exercise-induced weight loss was associated with physiological and biopsychological changes towards an increased drive to eat in the fasting state, this compensatory effect seems to be balanced by an improved satiety response to a meal and improved sensitivity of the appetite control system.

However, as Blundell pointed out, these mean changes hide the immense diversity between individuals.

Based on these studies it appears impossible to predict in advance how individuals will respond: Some people, in response to exercise, will be hungry and may overeat – others may find that they are much better in controlling their food intake.

Importantly, all subjects, irrespective of their body weight, showed a reduction in their amount of body fat and improvements in risk markers like physical fitness and blood pressure.

Thus, Blundell concludes, exercise does reduce body fat (even in people who do not lose weight) and has beneficial effects on important health parameters.

The answer therefore clearly is: no, exercise does not make you fat, but don’t expect to lose a lot of weight.

The many important benefits of exercise can, unfortunately, not be measured on a scale.

AMS
Edmonton, Alberta

Martins C, Kulseng B, King NA, Holst JJ, & Blundell JE (2010). The effects of exercise-induced weight loss on appetite-related peptides and motivation to eat. The Journal of clinical endocrinology and metabolism, 95 (4), 1609-16 PMID: 20150577

While there is no doubt that exercise is an important part of long-term weight management the exact role of resistance training (as opposed to aerobic or endurance training) remains unclear.

A paper by Barbara Strasser and colleagues from the University of Hall i. T., Austria, just published in Sports Medicine, describes a systematic review and meta-analysis of the effect of resistance training on metabolic risk factors in patients with abnormal glucose metabolism.

The authors identified 13 randomised controlled trials (RCTs) published between January 1990 to September 2007.

The number of participants in the individuals studies ranged between 17 to 120, with a pooled total of 425 participants in studies reporting HbA1c; of these, 219 participants received the resistance intervention. The mean age of the groups was between 46.8 and 67.6 years.

While resistance training reduced glycosylated haemoglobin (HbA(1c)) by 0.48%, fat mass by 2.33 kg and systolic blood pressure by 6.2 mmHg, it had no statistically significant effect on total cholesterol, HDL cholesterol, LDL cholesterol, triglyceride or diastolic blood pressure.

The authors concluded that resistance training has clinically significant effects on various components of the metabolic syndrome and should therefore be recommended in the management of type 2 diabetes and obesity.

While the paper only reports the effect of resistance training on fat mass (and not body weight), it does allude to the fact that participants also increased muscle mass, which will likely have made the actual change in body weight even smaller than the rather modest reduction in fat mass (~5 lbs).

Nevertheless, given the positive effects on glucose metabolism and blood pressure, these findings should certainly not discourage people from engaging in a reasonable amount of resistance training, even if the benefits are perhaps not measurable on a scale.

AMS
Toronto, Ontario

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Strasser B, Siebert U, & Schobersberger W (2010). Resistance training in the treatment of the metabolic syndrome: a systematic review and meta-analysis of the effect of resistance training on metabolic clustering in patients with abnormal glucose metabolism. Sports medicine (Auckland, N.Z.), 40 (5), 397-415 PMID: 20433212

For most people, dissatisfaction with their current weight is the biggest motivator to lose weight. This dissatisfaction is a direct function of an individual’s concept of what constitutes ideal weight. Thus a change in the perception of ideal weight, and thus in weight satisfaction, is likely associated with a change in weight-loss practices.

This notion is very much in line with a recent finding by Jennifer Kuk (CON Bootcamper!) and colleagues from Toronto’s York University, just published in the American Journal of Epidemiology.

Kuk and colleagues examined the relationship between self-declared ideal weight, body weight satisfaction and health practices among 15,221 men and 4,126 women in the 1987 and 2001 participants of the Dallas Cooper Clinic Aerobics Center Longitudinal Study.

Interestingly, participants in 1987 reported higher ideal weights than participants in 2001, an effect particularly pronounced from 1987 to 2001 for younger and obese men (85.5 kg to 94.9 kg) and women (62.2 kg to 70.5 kg).

Perhaps not unexpectedly, for a given body mass index, higher ideal body weights were associated with greater weight satisfaction but lower intentions to lose weight.

Body weight satisfaction was also associated with greater walking/jogging, better diet, and lower lifetime weight loss but with less intention to change physical activity and diet or lose weight.

In contrast, BMI was negatively associated with weight satisfaction and was associated with less walking/jogging, poorer diet, and greater lifetime weight loss but with greater intention to change physical activity and diet or lose weight.

Thus increased weight satisfaction, in conjunction with increases in societal overweight/obesity, may decrease motivation to lose weight and/or adopt healthier lifestyle behaviors.

On the other hand, as argued before, weight satisfaction may also be protective against weight cycling and negative psychological effects, which may well be as, if not more, troubling than carrying a few extra pounds.

It will clearly be of interest to determine where exactly the psychological benefits of weight satisfaction and failure to adopt a healthier lifestyle cancel each other out.

AMS
Edmonton, Alberta

OK, I am not actually on Oprah (yet?) - rather, this post is only about comments I was asked to make about Oprah’s “catastrophic” weight regain by Judith Timson, who interviewed me for her column, which appeared in yesterday’s Globe and Mail.

To read what Judith (and I) had to say - click here

Last week, Yoni blogged about the same topic - for his take on Oprah - click here 

I think Oprah has made the same mistake that most people make - they think there somehow must be a “cure”.

Unfortunately, there isn’t - there are only treatments - when you stop the treatment, the weight comes back - ALWAYS!

End of Story!

AMS
Edmonton, Alberta

With all the talk about obesity and its increasing role as the root cause of many chronic diseases (type 2 diabetes, osteoarthritis, and sleep apnea to name a few), you would think that health professionals are now regularly counseling their patients to manage their weight.

Well, this clearly does not seem to be the case, at least according to a new study by Jean Ko and colleagues from Johns Hopkins, Baltimore, MD, just published in Preventive Medicine.

Not only does this national (US) cross-sectional survey in over 1800 obese adults show that only around 40% of individuals reported being advised by their physicians to lose weight (this advise was more likely to occur in women and in people who also had chronic diseases), but that the advice given clearly did not reflect much understanding of obesity management.

Thus, although ample data show that exercise is NOT the most effective way to lose weight, this was exactly the advise given to 86% of the subjects. In contrast, changing diet, the best way to lose weight, was only recommended in 64%. Overall only 60% received the recommendation to both change their diet and to increase physical activity.

But the really scary finding of this study was the amount of weight loss recommended: 21%!

To put this into perspective - the average long-term result of the best behavioral intervention studies is 3-5% weight-loss, while adding pharmacotherapy to lifestyle results in long-term weight loss (while treatment continues) of only 10-15%. Sustained weight loss of 21% is in fact at the lower end of the average weight loss achieved by bariatric surgery (long-term weight loss in the SOS study was only 16%), which is generally in the 20-30% range.

I can well understand, when patients have ridiculous ideas about sustainable weight loss, but for health professionals to be advising unrealistic weight loss targets that are inconsistent with the ample evidence to the contrary is simply embarrassing!

I am convinced that few health professionals actually appreciate that for a 200 lb individual to lose 20% (=40 lbs), they are talking about a SUSTAINED energy deficit of 140,000 KCal. For a daily energy deficit of 500 KCal - difficult enough to achieve, let alone sustain - this would require at least 280 days (~ 9 months) of “dieting”.

In reality, because of the obligatory homeostatic counter-regulation that occurs with weight loss, to sustain this degree of weight loss, patients would need to maintain a diet that is generally well over 500 KCal less than they started out with. Always remember, that many of the successful weight-loss maintainers of the National Weight Control Registry are surviving on 1200-1400 KCal per day! (not very different from the effective caloric intake of a post-bariatric surgery patient).

As I have blogged before, managing your patients’ weight-loss expectations is sometimes more difficult than managing their weight.

For those who are not familiar with my recommendations:

1. The first step in weight management is STOP THE GAIN!

2. 5-10% sustained weight loss has clear health benefits.

3. The challenge in weight management is not losing the weight - it is keeping it off!

AMS
Edmonton, Alberta