Want to get your expenses under control? Don't buy with caffeine, study finds

They say never go shopping on an empty stomach. You'll end up bringing home half of the snack aisle. But according to a new study, it's not just what we eat that can affect our drinking habits, it's also what we drink. And if you're looking to stick to a budget, you might want to avoid caffeine.

Consuming caffeine can be bad for your budget.

The study, recently published in the Journal of Marketing, had a simple but ingenious design. The researchers set up a stand at the entrance of three home goods stores and department stores in Europe offering shoppers a free espresso. Some were given full strength brew while others were given decaffeinated. In exchange, shoppers had to complete a short survey about how they felt while shopping and share their receipts with researchers.

It will come as no surprise to coffee drinkers that those who receive a regular espresso report feeling more alert and excited when shopping. That's the purpose of caffeine, after all. But you probably didn't know that caffeine affects more than just your mood. It also apparently makes you more likely to hit your wallet.

Those who consumed caffeine purchased more items and spent more overall than those who received decaffeinated. They also bought different things. Those who had a regular espresso bought more decorative, non-essential items like scented candles and perfume. Purchases of more practical items, such as toilet brushes, remained relatively unchanged. Which suggests that when you get a little buzz after your morning brew, you're more likely to give in and make impulse purchases that you didn't plan on buying.

A takeaway dish in two stages

The lesson here for those looking to cut expenses is pretty clear. Coffee isn't bad for your body and may even be good for your health, but it can also make it easier to cut your budget. So maybe skip that second Americano before you hit the mall or start Amazon. More caffeine will not help you make the best financial decisions.

Those who operate retail establishments can learn exactly the opposite lesson from this study. Offering a free cup of coffee won't just make your customers happy, it might also inspire them to spend more at your store. Which means that whatever you invest in beans and an espresso machine can be more than offset by additional purchases. Worth trying at least.