Over 500,000 people visited Farnam Street last month to expand their knowledge and improve their thinking. Work smarter, not harder with our free weekly newsletter that's full of time-tested knowledge you can add to your mental toolbox.

How sugar helps you make better decisions

Consuming sugar makes one less impulsive. Aspartame, on the other hand, makes people more impulsive. So, if you run a casino, you should serve only diet soda. However, before you make a personal decision you should have a Coke.

In a recent paper published in Psychological Science, the relationship between the consumption of sugar (via a soft drink) and individuals' discounting rates was explored. Specifically, participants either consumed a soft drink containing sugar or one that contained aspartame (artificial sweetener).

The results indicate that when we have more energy available (that is, higher levels of blood glucose), we tend to be more future-oriented. The authors note that “the future is more abstract than the present and thus may require more energy to process. Blood glucose as brain fuel would strengthen effortful cognitive processing for future events.” Conversely, having low energy (or low blood glucose levels) may make an individual focus more on the present. The finding that a diet soda drink increased the degree of future discounting suggests that artificial sweeteners may alarm the body of imminent caloric crisis, leading to increased impulsivity.

The authors conclude that if controlling blood glucose levels may affect our decisions for later versus current rewards, then “reducing the degree of fluctuation in blood glucose may offer a possible means for the treatment and intervention of some impulsive disorders, anorexia, drug addiction, and gambling addiction.”


This study explored metabolic mechanisms of future (delay) discounting, a choice phenomenon where people value present goods over future goods. Using fluctuating blood glucose as an index of body-energy budget, optimal discounting should regulate choice among rewards as a function of temporal caloric requirement. We identified this novel link between blood glucose levels measured in the lab and future-discounting rates of participants, who made choices between a “smaller and sooner” reward and a “larger but later” option, with possible actual monetary rewards. A group of participants who drank a soft drink that contained sugar showed a reduced rate of future discounting afterward, when we controlled for sex, age, body mass index, and the taste of the drink. In contrast, a group of participants who drank a soft drink that contained artificial sweetener showed an increased rate of future discounting. Blood glucose levels not only varied as a result of caloric intake but also regulated the rate of future discounting, according to participants’ dynamic body-energy budget.

Study | Article

Long ago Google realized the importance of glucose in decision-making. As a result, they attempt to ensure that glucose is available and used properly.

Decisions take effort and too many of them make you tired.

To stay healthy, I recommend reading Gary Taubes two books Good Calories, Bad Calories and Why do we get fat and what to do about it.