Too much choice makes you fat

The human organism is an amazing work-in-progress that has been shaped by millions of years of evolution. As a result much of our behaviour may not be as free as we think.

We make unconscious decisions all the time that result from instincts that have been passed down to us over the millennia. In our distant past these instincts would have provided an adaptive advantage, however, in the hustle and bustle of today’s modern cities many of these instincts actually work against us. If you are serious about taking control of your diet you need to be aware of how your unconscious desires are leading you astray.

Life has existed on this planet for around 3.6 billion years. The first mammals emerged 200 million years ago and the first primates around 60 million years ago. The first fast food restaurant opened its doors just over 100 years ago.

The Variety Effect

One of the most interesting unconscious drives is the variety effect. The variety effect has been observed by many different researchers and has been repeatedly confirmed in controlled studies. The simplest definition of this effect states that human beings will eat more when there is a greater variety of food available. Seems pretty obvious right? You’re at an open buffet and you pile your plate high, sampling as many dishes as possible. But the variety effect goes deeper than this.

The variety effect has been shown to work in three main ways.

More dishes lead to more calories being consumed. As in the above example; if pizza, fried chicken, burgers and ice-cream are all available you will consume more calories than if there were just one of these four foods available. The evolutionary logic is clear. Omnivores have a selective advantage because of the greater number of dietary options available to them; it was probably best for our ancestors not to be tied to one specific food source in case this item became scarce or disappeared completely. Also, the preference for sampling a wide variety of foods, rather than gorging on just one, meant that our ancestors were less at risk if one of the many different foods they consumed were contaminated.

More flavors lead to more calories consumed. It has been demonstrated that even if there is only one available food item, more of it will be consumed if there are more flavors available. This is used to devastating effect by marketers who offer us the same thing in an increasing number of varieties (e.g. ice-cream, yoghurt, cookies, jellybeans). One experiment showed that when more varieties of a product were placed on a supermarket display stand (different flavors of jam), 20 percent more customers stopped at the stand.

Odourless and tasteless variety still leads to more calories being consumed. In a landmark study by Barbara Kahn and Brian Wansink it was demonstrated that by controlling the number and distribution of M&Ms given to different groups of test subjects, they were able to increase consumption by an amazing 77%. Greater variety of colours caused subjects to eat more even though M&M’s all taste and smell the same. Similar results have also been obtained by using different shapes of pasta. Ever wonder why companies release so many different versions of the same thing? Remember the craze for “minis” a few years back? Now you know why.

Knowledge is power

Why do you need to know all this? Well you can bet that the companies trying to market their products to you all day long are aware of this research, it informs their product development, their advertising, and the ways they present their items on supermarket shelves. A little knowledge goes a very long way, so being aware of the variety effect means it has less power over you and allows you to be more conscious of the choices you are making. We promise you, you will never look at a buffet cart, mall eatery, or supermarket shelf in the same way again.


Abigail K. Remick, Janet Polivy, and Patricia Pliner, “Internal and External Moderators of the Effect of Variety on Food Intake,” Psychological Bulletin 135, no. 3 (2009): 434-51; Leonard H. Epstein et al., “What Constitutes Food variety? Stimulus Specificity of food,” Appetite 54, no. 1 (2010): 23-29.

Barbara J. Rolls et al., “Variety in a Meal Enhances Food Intake in Man,” Physiology & Behavior 26, no. 2 (1981): 215-21.

Barbara E. Kahn and Brian Wansink, “The Influence of Assortment Structure on Perceived Variety and Consumption Quantities,” Journal of Consumer Research 30, no. 4 (2004): 519-33.

Barbara J. Rolls, Edward A. Rowe, and Edmund T. Rolls, “How Sensory Properties of Foods Affect Human Feeding Behavior,” Physiology & Behavior 29, no. 3 (1982): 409-17.

Raynor, H. A., & Epstein, L. H. (2001). Dietary variety, energy regulation, and obesity. 603 Psychological Bulletin 127 no. 3, 325-341.

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