How Loss Aversion Affects Our Perceptions of Weight

Disclaimer: This article is not intended to provide health or medical advice. Consult your doctor about making changes to your diet or exercise routine.

With vaccination rates increasing and the country opening up, I considered flying to a neighboring province to enjoy some version of a vacation. Much to my delight, I found flights at ridiculously low prices—only to check back the next morning and discover that the cost of a ticket had doubled.

And so began my morning of obsessively tracking, refreshing, and searching for cheaper flights. The original price became my “ideal price,” and anything higher felt like a loss. It wasn’t until hours later I realized that I had fallen prey to loss aversion (with a hint of anchoring bias).

Loss aversion in everyday life

One of the key tenets of behavioral science, loss aversion is a concept that comes out of Kahneman and Tversky’s prospect theory. This theory demonstrates how we register losses more acutely than we do gains, and that we tend to make decisions in the interest of avoiding potential losses. This knowledge has wide implications in several domains, especially in finance, insurance, and economics.

But how does this bias shape decisions that aren’t related to money? Early research shows that prospect theory and its related behaviors may extend to how we view weight loss.

Loss aversion and weight loss

A group of researchers from the University of Kansas and the University of Missouri surveyed college students, gathering data on their BMI and eating behaviors, and assessed whether they believed they were in control of their weight.

Participants then participated in a decision-making task where they chose between a risky gamble (with a 50% chance of winning) and a guaranteed reward. (Note that in both cases, the rewards were hypothetical.) Some of the prizes were monetary (e.g. winning $10), while others related to body weight (e.g. losing 10 lbs).2

Participants showed similar risk preference and loss aversion attitudes to weight as they did to monetary choices—in other words, people who were averse to losing money also demonstrated a weight gain aversion.

Notably, this result did not differ between participants who were satisfied with their current weight and those who were not. In other words, the way in which people valued potential weight loss did not correlate with their actual body mass. Moreover, the threat of weight gain loomed larger than the opportunity of equivalent weight loss: people registered it almost twice as much.

Implications

So, early science suggests that we may react more strongly to weight gain than weight loss. These findings have important implications for weight maintenance recommendations.

For starters, many experts recommend daily “weigh-ins” for those trying to lose weight. Studies have shown that those who weigh themselves daily lose more weight3 and maintain that weight loss for a longer period.4 The underlying reason is thought to be that regular weigh-ins may help individuals “catch” the weight gain early on, and adjust their behavior accordingly.5 This habit serves as a way of obtaining feedback, which is an important tool for behavior change and improving self-control.6

However, there isn’t consensus on this recommendation, and recent research has found that people who regularly monitored their weight did not lose significantly more weight than a control group.8

Moreover, what we know about loss aversion suggests that daily weigh-ins may not be a good idea for those who are especially loss averse (or in this case, weight gain averse). It’s important to recognize that weight fluctuation can be as unpredictable as the stock market: the amount of salt, food, and water somebody consumes, hormonal fluctuations, and even changes in the weather can cause a weight spike.9 By regularly checking weight on the scale, we may be unnecessarily exposing ourselves to fluctuations that are beyond our control.

Creating the conditions for loss aversion to rear its head could ultimately backfire, because as with so many other cognitive biases, it doesn’t always lead us to make the best decisions. Loss aversion influences our ability to perform well financially, narrow down options in a decision or even design a pizza. When losses loom, we may act irrationally and make choices that aren’t in our best interest.

How might these behaviors manifest in weight regulation? When faced with weight gain, some individuals engage in several dangerous behaviors, such as unnecessary dietary restriction, yo-yo dieting, and overtraining, which can be counterproductive when trying to achieve a weight-related goal.

Managing weight gain aversion

The reality is, sustainable weight loss is a long-term game. Similar to recommended investment plans, finding a health plan and “staying the course” is often the best strategy, but we risk exposing ourselves to more fluctuation by doing so. “Crash diets” are popular because they promise a simple solution to the problem at hand, but they are never sustainable (and are often damaging to our health).

Our knowledge of prospect theory and loss aversion has helped us improve our financial decision-making. Likewise, this preliminary evidence on weight gain aversion can help us develop strategies for coping with weight fluctuations.

  • Put losses into perspective: Asking what the worst outcome would be if you weren’t to react now might help reframe potential loss and stay the course of an intended decision.9
  • Be skeptical: If you’re feeling insecure, it’s easy to be tempted by “quick fixes” like crash diets. Researching these so-called “solutions” and their long-term implications may help you stick with your plans.11
  • Consider skipping the scale: Regarding investment decisions, Daniel Kahneman stated: “Closely following daily [stock market] fluctuations is a losing proposition, because the pain of the frequent small losses exceeds the pleasure of the equally frequent small gains.” Knowing that we have weight gain aversion, this advice may have utility in the weight loss field as well.12
  • Remember that our biases have a purpose: In some situations, it’s probably a good thing we are loss averse because it makes us question risky decisions. In finance, classic strategies we use to avoid losses include diversifying our financial portfolio.13 In health and wellness, similar actions, such as building healthier daily habits, could help us “hedge” against unhealthy downward spirals.

While preliminary research exists, more research is required to understand how behavioral economics concepts like loss aversion influence weight loss. Researchers may also seek to validate whether the kinds of interventions used to improve financial decision-making could also help individuals stick to weight loss–related goals.

Other questions that remain include whether or not this same behavior occurs for those trying to gain weight (e.g. trying to bulk up and put on more muscle). As well, the use of neuro-imaging and other tools from neuroscience may be helpful in better understanding this phenomenon. But for now, it may be helpful to consider that our current knowledge of loss and risk aversion extends beyond the realm of finance and into our other day-to-day behaviors.

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