Book review: "Secrets from the Eating Lab" by Traci Mann

[Hapless Bills Fan]

Traci Mann is a professor of psychology at U of Minn.  From her blurb: "She is a widely cited expert, but she does not run a diet clinic or test diets, and she has never taken a penny from commercial diet companies, sat on their boards of directors, or endorsed one of their products. Because of this, her livelihood, research funding, and reputation are not dependent on her reporting that diets work or that obesity is unhealthy. This sets her apart from nearly all diet and obesity researchers and allows her to speak the truth about these topics, which she does with abandon."

Her book, "Secrets from the Eating Lab", is an eclectic mix of the fascinating and the mundane.  Her lab specializes in conducting research around what influences eating behavior and how.  Example: put out food items (a bag of chips vs an apple) for people registering for a conference, and looked at how many registrants took the apple when it was labeled "healthy" vs when it had a healthy heart symbol vs when it was just labeled about its origin (this delicious apple was developed at the University of Minnesota's experimental farm).  Conclusion: don't label an apple "healthy" if you want people to eat it, but attractive symbols may work.

TL;DR: she summarizes a buttload of evidence that conventional calorie-reduction-and-exercise diets simply don't work to produce lasting weight loss and in fact create psychological and physiological changes that make subsequent weight control more challenging; that exercise by itself produces many of the positive health effects attributed to weight loss whether or not someone loses weight (lower blood pressure,  improved glucose control, etc); and that the best health strategy may be to change behaviors to exercise regularly, minimize temptations and maximize intake of healthy food to live on the "low end" of one's intrinsic set point weight.  Some of her behavior change strategies are novel to me and I'll try 'em.

Example of the fascinating: an experiment where they asked volunteers to come into the lab 2x and allow an IV to be placed to draw blood samples during a tests (of course the order of the tests was randomized and all that good experimental stuff).  For one test, they were given a milkshake described as "decadent, indulgent, 640 calories".  For another, the shake was described as "nonfat, guilt-free, 140 calories".  Levels of the hormone ghrelin (which signals hunger) were measured before, during, and after the shake consumption.  The level of ghrelin declined sharply after participants consumed their indulgent shake but remained the same after the guilt-free shake consumption.  Here's the thing: unbeknownst to the participants, they were given the exact same milkshake each time.  Only the description changed.

I've never seen a clearer demonstration of the power of our thoughts over our biology with regard to food consumption.

Ultimately, though, Mann's book leaves my scientific ghrelin levels unchanged.  She references a biological "set point" constituting a range of (say) 20-30 lbs beyond which it is difficult to either gain or lose weight and she summarizes some evidence supporting this concept (studies of identical twins separated at birth show weight correlates to each other and to birth parents, but not to the families that raised them).  However, her book does not discuss at all: if a "set point" exists - what is the evidence of what sets it or changes it beyond genetics?  Because clearly, some people do manage to lose weight beyond that limited 20-30 lb range and maintain that weight loss for years; while other people who have been stable at a reasonable weight for years will,at some point, gain weight beyond that 20-30 lb range for one or another reason and then struggle to lose it.  So if set points exist, there seems to be significant evidence that they are influenced by factors beyond genetics, and can be changed, raising the question is "what are those factors? how are they triggered?"  She doesn't go into that at all, leaving me hungry for answers.
 

A subsidiary question: Mann delineates the hormonal and psychological changes caused by dieting (increased cortisol or "stress hormone"; changed responses to availability of tasty food).  She cites the famed Keyes "Minnesota Starvation Experiment" of WWII in which 36 CO volunteers spent 6 months on a "starvation" diet of 1500 calories a day and lost 25% of their body weight so that different "refeeding strategies" applicable to WWII refugees could be tested.   In that experiment, the volunteers were fed horrible meals of potatoes, bread, rutabagas, turnips, and cabbage and suffered debilitating psychological effects - lethargy, fixation on food, loss of interest in regular activities or studies.  But given the results of the "Milkshake Experiment" showing a physiological effect of perceived food quality - one can't help asking, if the same experiment had been performed but using food perceived and described as "gourmet" and "luscious" (and also varied, and including more 'normal' foods) vs "starvation" - would the mental effects of the diet have differed?  Would it have been less mentally and socially debilitating?