Dietary trickery

Palatability is an important factor to consider, as individual preferences will always influence a subject’s perceived fullness. Measures to control for this were taken by serving 27 of the 38 foods under an opaque plastic hood, to minimise influences of sight and smell, as well as preconceived ideas of the level of fullness a certain food “should” elicit (11 of the foods contained liquid; for example, breakfast cereal with milk, and hence could not be served in small pieces via a hole in the hood).

It makes sense that the more palatable a food, the lower the SI, which is generally the case with high fat foods, as humans have an innate liking of the “rich” mouth feel and taste of fat. This has been hypothesised to maximise the intake of energy-rich fuel (fat is the most energy-dense nutrient) during periods of food abundance in our evolutionary past, in preparation for inevitable times of scarcity. However, today’s times are of abundance, and it is easy to passively over-consume energy via fatty foods, such as cake and french fries. High-fat foods seem to be less capable of proclaiming, “I’m here and I’ve got lots of yummy energy for you” loud or fast enough for our bodies to hear.

In conclusion, the SI ideally illustrates the fact that a calorie is NOT a calorie, i.e. not all kJs are equal. Eat 1000kJ of a fat-laden food and feel less full than after an isocaloric (equal energy) portion of a protein-rich food. In addition, different foods promote varying levels of dietary-induced thermogenesis (DIT, heat production) and fat storage. So, both sides of the energy balance equation have the potential to be manipulated; eat more filling foods to decrease food intake and foods that promote DIT and decrease fat storage to maximise energy output.

The SI is an important concept that has thus far been under-utilised and has huge potential as an anti-obesity tool. So, after reading this article, I’m afraid to say any excess fat “IS your fault”, as now you are equipped with the knowledge of how to identify those foods which try to “go behind your back” and trick your body into letting more of them in. Revert to a more traditional diet, full of foods that score high on the SI, such as porridge, fruit and fish, and stop such “dietary trickery” now.