Who Should and Who Shouldn’t Eat Before Going Grocery Shopping

Image of groceries in a basket.


A common piece of conventional wisdom states that you should never go grocery shopping on an empty stomach. Intuitively, this makes sense: if you’re already full when you go to buy food, you’ll be less tempted to buy extra food items.

However, studies on the topic discovered that this is not always the case. Rather, while this is true for people who are not overweight, people who are overweight sometimes buy more food if they eat before shopping.

In the following article, you will read more about the topic, and see some suggestions for how to decide whether you should go shopping when you’re feeling hungry or when you’re feeling full.


Should you go shopping when you’re hungry or when you’re full?

Studies show that for most people, eating before going grocery-shopping is a good idea:

  • One study found that short-term food deprivation, in terms of not eating for a few hours, led people to buy more high-calorie products, such as candy and salty snacks.
  • Another study found similar results, so that when people were hungry, they were interested in buying more food items compared to when they are full.

However, neither one of these studies differentiated between overweight and normal-weight participants. On the other hand, studies which did examine the shopping patterns of overweight participants compared to participants with a “standard” weight, showed that there is a significant difference between the two groups:

  • A study which looked at purchasing behavior in a large supermarket found that people with a standard weight tend to purchase more food when they are hungry, while overweight people tend to purchase less food.
  • A different study showed similar results, where “normal individuals bought more food if they were deprived than they did if they had recently eaten. Overweight individuals actually bought more food if they had recently eaten than they did if deprived.”

Based on this, the general advice on the topic is the following: if you are overweight, it’s generally preferable to go food shopping on an empty stomach, while if you’re not overweight, it’s generally preferable to go food shopping on a full stomach.

In the next sections, we will see what the science says about this difference between people who are overweight and those who are not, and learn what you can do to make sure that you pick the option that works best for you.


Explaining the difference in shopping patterns

Researchers are not entirely certain what leads to this difference between people who are overweight and those who are not.

One suggestion is that for people with a standard weight, increased hunger leads to increased impulse buying, as evident in the fact they purchase more items than they expect to. Conversely, when overweight people eat before grocery shopping, they might become more focused on food, which preemptively increases their intention to buy extra food.

This is reflected in the fact that people with a standard weight tend to overshoot their estimated bill when buying food on an empty stomach, while overweight participants tend to decrease both their estimated bill as well as the amount of food they buy in practice.

Another possibility which could explain why some people tend to buy more food or more unhealthy food when they’re full, is that when you’re full, you sometimes feel like you’re interested only in comfort food such as snacks or desserts, which are generally perceived as more appealing.

Conversely, when you’re hungry, both healthy as well as unhealthy food looks appealing to you. If this effect is more pronounced in overweight people, then it could explain the difference in shopping patterns between them and non-overweight people.

Finally, it’s also possible that for overweight people, being hungry is more likely to be indicative of the fact that they’re dieting, which could explain their reduced intention to purchase food when they go shopping on an empty stomach. However, it’s unlikely that this could explain the effect entirely, since studies that accounted for this variable still found the same shopping patterns as studies that didn’t.

Overall, it’s difficult to say why exactly this phenomenon occurs, where overweight people buy more food when they go grocery shopping on a full stomach, while people with a normal weight buy less food.

Nevertheless, since this finding was confirmed in several studies on the topic, it’s certainly something worth taking into account when you go shopping. Most importantly, it means that the notion of “never go grocery shopping on an empty stomach” isn’t necessarily true for everyone.


The role of individual variation

When it comes to the psychology of dieting, there is always going to be some individual variation. This means that the various factors that come into play when it comes to deciding what food to buy will affect different people in different ways. A good example of this is the fact that, as we saw earlier, your weight is an important factor, that controls how hunger affects you when it comes to buying food.

However, the guidelines that we saw here represent general tendencies, rather than behavioral patterns which are always observed. This means that if you’re overweight, for example, then you will most likely benefit more from going grocery shopping on an empty stomach, but not necessarily. Rather, it’s possible that personally, you will find it easier to buy less unhealthy food if you go shopping on a full stomach.


Figuring out what works for you

Due to the role that individual variation may play, the best way to find what works for you is to try the different options out, and test which one leads to the best outcome. One way to do this is to keep shopping as you normally do, while paying attention to what you buy, and to how hungry you are at the time.

If you do this, it might immediately become obvious that when you’re hungry or full, you tend to buy a lot of snacks. In cases when it is not so obvious, you can keep receipts from your purchases, and write on each one how hungry you were when buying the food. Then, after you’ve collected several receipts, try to compare the type of purchases that you make when you’re full, compared to the purchases that you make when you’re hungry.

Furthermore, you can also try to actively alternate between going grocery shopping while you’re hungry and while you’re full, so that you can easily compare the amount and type of food that you buy each time.

Regardless of whether you choose to track food purchasing in a passive way, or to actively alternate between shopping when you’re hungry compared to when you’re full, you should try and ensure that your results are accurate by minimizing the influence of external variables (which are known as confounds), such as going shopping with other people versus going alone.

The more information you have on your shopping behavior, based on the number of time you go shopping, the more accurate your results will be in general. However, in most cases, it’s likely that after several rounds of purchases you’ll have a pretty clear answer.

Overall, at the end of the day, it’s important to not only understand what research says works in general, but to also realize that there is a lot of individual variation in terms of which solutions work for different people. In order to find the best option, you should rely not only on the generalized guidelines, but also try things out yourself, in order to find the solution that works best for you.


Summary and conclusions

  • People who are not overweight generally tend to buy less food when they go grocery shopping on a full stomach. Conversely, people who are overweight tend to actually buy less food if they go shopping when hungry.
  • These purchase behaviors are attributed to the fact that when non-overweight people go grocery shopping while hungry, they tend to make more impulse purchases. Conversely, when overweight people go shopping while they’re hungry, they end up feeling less focused on food, which helps them reduce their intention to purchase extra food from the start.
  • This effect of hunger on shopping intention remains significant even after controlling for background factors such as dieting.
  • There is a lot of individual variation involved when it comes to deciding whether you should go shopping when you’re hungry or when you’re full, as evident in the fact that people with different weights generally benefit from different options. Accordingly, these guidelines should be viewed as general advice, which can guide you to make the best decision, but which won’t necessarily indicate which option will work best in your case.
  • In order to find the solution that works best for you, you should track your purchasing behavior over time, in order to identify whether you tend to purchase more unhealthy food when you’re hungry or when you’re full. If you decide to do this, try to control for background factors as much as possible, such as the time of day in which you go shopping.