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

Recent population surveys show that as many as two out of three women will report trying to lose weight in the past year.

Obviously, this answer does not really tell us much about what women are actually doing, as the types of diets and weight loss strategies seem virtually countless - some perhaps healthier than others.

Now a study by Stephanie Lanza and colleagues from Pennsylvania State University, published in the latest issue of OBESITY, suggests that women’s weight loss strategies can be divided into four common strategies and that simple questions can help predict these behaviours.

The study used a statistical method called latent class analysis (LCA) to identify subgroups of individuals who shared similar patterns of weight-control strategies amongst 197 non-Hispanic white women living in central Pennsylvania by analysing their response to 14 commonly used healthy and unhealthy weight-loss strategies.

Four groups were identified:

“No Weight Loss Strategies” (10%): individuals in this group are characterized by a low probability of reporting any weight-control strategy.

“Dietary Guidelines” (26.5%): individuals in this group have a high probability of reporting use of strategies consistent with healthy practices present in current guidelines, such as increased fruits and vegetables intake, increased exercise, decreased fat intake, eliminating certain foods, and reducing calories.

“Guidelines+Macronutrient” (39.4%): individuals in this group, in addition to the healthy practices of the guideline users, also have a high probability of reporting trying a low-carbohydrate diet.

“Guidelines+Macronutrient+Restrictive” (24.2%): individuals in this group report having tried nearly all weight-loss strategies, including both healthy and unhealthy strategies. This is the only subgroup of individuals who were likely to report skipping meals; use of appetite suppressants/liquid diets/diet pills; reducing alcohol consumption; and fasting.

Perhaps not surprisingly, women with weight concerns, the desire to be thinner, and dietary restraint were far more likely (in fact 10 to 30 fold more likely) to be in the “Guidelines+Macronutrient+Restrictive” class than in the “No Weight Loss Strategy” class.

The relationship between disinhibition and behaviour was more complex: disinhibition increased the odds of engaging in any weight-loss strategy when restraint was low; whereas, disinhibition increased the odds of engaging in unhealthy compared to healthy weight-loss strategies when restraint was high.

The authors interpret these findings to suggest that being both highly restrained and disinhibited may be a strong predictor of unhealthy, extreme weight-loss behavior that may ultimately be counterproductive.

As a clinician, I wonder if the identification of these behavioural classes will help better manage patients in these classes or even provide reasonable predictors of attrition and outcomes in clinical weight management programs. My guess is that individuals in the “Guidelines+Macronutrient+Restrictive” will pose a far greater clinical challenge than individuals in any of the other classes.

Clearly, in the same manner that obesity is not a homogeneous disorder, weight control behaviours come in different flavours - something that should perhaps never be forgotten in counseling.

AMS
New York, New York

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Lanza ST, Savage JS, & Birch LL (2010). Identification and prediction of latent classes of weight-loss strategies among women. Obesity (Silver Spring, Md.), 18 (4), 833-40 PMID: 19696754

Yesterday, I presented Grand Rounds at the Holy Cross Pain Centre in Calgary. As regular readers will recall, pain is a common consequence and/or cause of weight gain and very often a major barrier to weight management.

Not only is obesity commonly associated with conditions such as fibromyalgia, back pain, osteoarthritis, or plantar fasciitis but also migraines and other forms of headaches.

In the same manner that obesity is a complex syndrome that has a multitude of psychosocial and biological determinants, so is chronic pain. It was therefore not surprising to see that many of the principles of interdisciplinary pain management used at the Holy Cross Pain Centre are not very different from the principles we use in the Weight Wise program.

The team at the Pain Centre is fortunate to have the support of physio- and occupational therapists, nurses, psychologists, pharmacists, dietitians and other allied health professionals as well as a wide range of physician consultants working at their centre.

This complement of health professional is indeed very similar to what we have in our obesity clinic.

There are other important similarities: managing patient expectations, emphasis on self-management, focus on functional goals, attrition rates, and other characteristics of chronic disease management programs.

As I have often blogged, obesity is not really different – it just takes the same approach and resources to manage as other chronic conditions – no more, but also no less!

AMS
Calgary, Alberta

I have often heard from my patients that with previous weight loss attempts they not only gained all of their weight back but in fact gained additional pounds, making them heavier than they ever were before - in other words, they report to have dieted themselves “fat”.

Does this in fact happen? Is excess weight gain perhaps even a natural consequence of trying to control your weight by dieting?

This question was now addressed by Jennifer Savage and Leann Birch from Pennsylvania State University in a study published this month in OBESITY.

A total of 176 women were assessed at baseline and followed over four years. Three groups of women were identified: those making no effort to control their weights (N; 23%), those using healthy strategies (H; 43%) and those using both healthy and unhealthy strategies (H+U; 35%).

Despite adjustment for numerous confounders like education, income, and initial BMI, women using both healthy and unhealthy strategies (H+U) gained significantly more weight (4.56 kg) than the N group (1.51 kg) and H group (1.02 kg) over the four year observation period.

Interestingly, these differences were already apparent in the third year, when the H+U group gained significantly more weight (2.86 kg) than the H group (0.03 kg) and N group (0.44 kg).

Perhaps not surprisingly, the H+U weight control group had higher scores on weight concerns, dietary restraint, and had poorer eating attitudes than women in the H or N groups.

Healthy strategies included reducing calories and amount of food, eliminating sweets, junk food and snacks, increasing activity, eating more fruit and vegetables, eating less fat or less high-carb foods, and eating less meat.

Unhealthy strategies included skipping meals, using diet pills, liquid diets, appetite suppressants, laxatives, enemas, diuretics, and fasting.

These findings suggest that self-reported weight control attempts do not necessarily lead to large weight gains, but using unhealthy strategies to control weight does.

As the authors point out, the main reason that women who used healthy weight control strategies were probably more successful was simply because these strategies are more sustainable than the unhealthy strategies like fasting, skipping meals or using liquid diets or pills, which may simply lead to loss of control, overeating and excess weight gain over time.

Another important aspect of this study noted by the authors is that women with greater weight concerns were apparently more likely to engage in unhealthy practices thus setting themselves up for greater weight gain in the long run. This point, if validated in other studies, clearly sends a warning that simply promoting weight concerns may actually exacerbate weight problems in the long run.

Thus, providing proper guidance on healthy weight loss strategies is essential to avoid making the problem worse than it already is.

On the other hand, the study also shows that women who adopt healthy weight control techniques can very much minimise weight gain over time, even if no actual weight is lost in the long run.

AMS
Edmonton, Alberta

Calories are the currency of weight management and any weight loss diet has to offer fewer calories than the body needs.

However, the means by which this caloric deficit is best achieved remains an area of continuing debate. While the proponents of ketogenic low-carb diets cite the greater ease of lowering weight, proponents of low-fat diets extol the putatively greater benefits on lipid profiles.

Nevertheless, previous studies have clearly shown that in the end both strategies lead to the same amount of weight loss, even if the low-carb approach may initially seem more effective.

This observation is once again confirmed in a new study by William Yancy Jr and colleagues from the Veterans Affairs Medical Centre, Durham, NC, published in the latest issue of the Archives of Internal Medicine.

In this study 146 overweight or obese outpatients (mean age 52 yrs) were randomized to either a ketogenic low-cab diet (initially <20 g of carbohydrate daily) or the lipase inhibitor orlistat (120 mg TID) combined with a low-fat diet (<30% energy from fat, 500-1000 kcal/d deficit) over 48 weeks.

Of the initial participants, 79% completed the low-carb arm whereas 88% completed the orlistat plus low-fat diet. Weight loss was similar between the groups, with participants losing around 9% of their initial body weight on either diet.

While the low-carb diet appeared to have a more beneficial impact on blood pressure, the orlistat low-fat combination appeared to have a greater beneficial impact on LDL-cholesterol.

However, in the end it is probably fair to say that both approaches led to more or less similar improvements in body weight and related risk measures, showing once again that this is probably not so much about which diet is more effective as it is about which diet works best for you.

Thus, in clinical practice it is likely that some patients will find it easier and preferable to severely restrict their carb intake, while others may find it easier to reduce their calories from fat by taking orlistat and reducing the fat in their diet.

The bottom line in both case is that the benefits will only persist as long as the participants stay on their respective diets or treatments. This makes it even more critical that patients chose the strategy that works best for them and that they are most likely to stay on in the long term.

Remember, neither diet is likely to “cure” obesity. As with all obesity treatments, when the interventions stop the weight comes back.

AMS
Edmonton