Over the last few years pre-packaged meal kits have quickly become a multi-billion dollar industry. The straightforward simplicity of being home-delivered a box containing a recipe and exact quantities of pre-packaged ingredients has proved to be well-suited to busy 21st century lifestyles. However, critics of meal kit services have suggested the product may have a devastating carbon footprint due to the increased plastic waste of packaging each individual ingredient for every meal.

But is this actually true? Do meal kits have a larger carbon footprint than regular grocery store shopping? A team of environmental researchers from the University of Michigan set out to crunch the numbers by completing what is called a comparative life-cycle assessment, calculating the total greenhouse gas emissions of an average meal kit dinner compared to the same meal cooked at home from ingredients bought individually at a grocery store.

"Meal kits are designed for minimal food waste," explains Shelie Miller, senior author on the new study. "So, while the packaging is typically worse for meal kits, it's not the packaging that matters most. It's food waste and transportation logistics that cause the most important differences in the environmental impacts of these two delivery mechanisms."

Overall, the research concluded a single store-bought meal produced 33 percent more greenhouse gas emissions than the equivalent meal kit. This final result was calculated by offsetting the emissions from a meal kit's increased packaging against the product's lower last-mile transportation emissions, reduced food waste, and streamlined supply chain.

Food waste for example, played a big role in the study's calculations. Grocery store shopping was found to result in significant wasted food, both at point-of-sale (stores discarding unsold and spoiled food) and at the consumer end (individuals purchasing larger volumes of ingredients than are specifically needed, and throwing out volumes of uneaten leftovers).

"Even though it may seem like that pile of cardboard generated from a Blue Apron or Hello Fresh subscription is incredibly bad for the environment, that extra chicken breast bought from the grocery store that gets freezer-burned and finally gets thrown out is much worse, because of all the energy and materials that had to go into producing that chicken breast in the first place," says Miller.

The other major metric examined was supply chain and transportation emissions. The supply chain structure for a meal kit involves more efficient and direct food transportation to a single factory, from which the last-mile to consumer consists of a single truck journey delivering many meals. This results in lower overall emissions than if a consumer took a personal vehicle to a grocery store to obtain ingredients for a given meal.

While the study is impressively exhaustive in its examination of the subject, it does obviously rely on many factors that can be quite easily moderated by individual consumers. It assumes a consumer travels to a store to buy groceries for every individual meal, and it is also assumes there are large portions of food waste for every meal, both in unused groceries and uneaten leftovers. These two factors certainly are not indicative of every consumer out there, so it is fair to say that many non-meal kit meals being produced do not have the large carbon footprint used as a standard in this study.

Brent Heard, lead author on the study, also suggests there inevitably is plenty more that meal kit companies can do to better reduce their carbon footprint, including improving the efficiency of packaging processes and reducing volumes of emission-heavy products such as red meat.

"Meal kit manufactures could reduce their environmental impacts further by doing all they can to minimize food loss in the pre-portioning process," says Heard. "They could also reduce packaging to the minimum necessary to protect and contain pre-portioned food. They could choose refrigerant packs that are as benign as possible (i.e. largely water-based), and they could consider limiting how many environmentally intense food products (such as red meat) are offered on their menus."

Ultimately, this research arguably suffers from too many caveats to generally conclude meal kits are more environmentally friendly than regular grocery shopping. However, it does function as a valuable reminder that food waste and transportation emissions are just as important as plastic packaging when considering the overall carbon footprint of a consumer's lifestyle choices.

The study was published in the journal Resources, Conservation and Recycling.