Home delivery meal kits can slash food waste by more than two-thirds, but suppliers need to switch to reusable packaging to make them environmentally friendly, researchers say.

Tailor-made meal kits save waste by providing people with precise amounts of fresh ingredients for chosen recipes, meaning leftovers are minimised and less food goes off before people have a chance to use it.

But while the delivery services score well on reducing food waste, buying the same ingredients from the supermarket almost always saves energy overall simply because meal kits use so much single-use packaging.

“The good news is that if you have meals that are tailored for consumption, people won’t over-buy and you have less food waste. You fine-tune the portions to what people will actually eat,” said Michael Webber, acting director of the Energy Institute at the University of Texas in Austin.

Beyond the cost of the waste itself, discarded food generates methane that contributes to climate change. If food waste was a country, it would rank third in emissions behind the US and China. A 2018 report from the Boston Consulting Group found that the waste was set to soar by a third by 2030 when global food waste was estimated to reach 2.1bn tonnes.

According to Webber, meal kits can reduce transport emissions if they mean people take fewer trips to the supermarket. If people only went to buy non-perishable goods such as soap and toilet paper, they may only have to visit once every couple of months, he said. “That delivery truck can carry meals for you and dozens of neighbours, so you might replace dozens of car trips with one truck trip,” he added.

The study found that even if delivered meal kits reduced food waste to zero, they would still use up more energy overall than buying the same food from the supermarket unless the energy used for the meal kit packaging was cut by a fifth. Details of the study were presented on Thursday at the American Association for the Advancement of Science meeting in Washington DC.

“The packaging is a killer if it’s single-use and thrown away. All the environmental benefits are lost,” said Webber. “But if the packaging can be reused, if it’s glass bottles, like in the old days, you can get some benefits.”