In the next three decades the human population is set to rise by some 2.5 billion. It will take all our ingenuity to feed everyone. Luckily, there are already many smart ideas on the table. But we can all play a part by rethinking what we eat so that Earth’s limited resources are used more efficiently. So, which foods and drinks should we cut back on?

1. Beef

When it comes to wasting precious resources, animal products are tops – and nothing beats beef. Land devoted to feeding cattle could provide 10 to 20 times more protein if it were planted with legumes. What’s more, to produce 1 kilo of beef, you need 15,000 litres of water – that’s more than three times as much as for chicken and some 18 times what’s needed for a kilo of wheat.

2. Shrimps

It takes 25 kilograms of feed to get 1 kilo of beef. Seafood is far more energy efficient, but shrimps less so than other species. Norwegian Atlantic salmon, for example, need to eat just 1.15 kilos to provide a kilo of fish. Shrimps must down about double that to give the same amount of seafood on your plate.

3. Nuts

Growing them requires vast amounts of water. – each nut requires as much as 4.5 litres to produce. Walnuts, cashews, hazelnuts and pistachios are almost as bad. Chestnuts are a much better choice to save the world’s scare water resources.

4. Fries

In the UK, , making them the most wasted food of all. Fries are particularly bad because fast-food restaurants regularly toss them out if they are not sold within 5 or 10 minutes of preparation. In addition, land used to produce fats for frying could give more calories if vegetables were grown on it instead.

5. Coffee

Tea requires more land to produce than coffee, but coffee has another vice. For each cup you drink, a coffee plant has consumed 550 cups of water. Add fancy flavourings and the damage is far worse. It takes around 35 litres of water to produce a single gram of nutmeg. Vanilla is twice as thirsty, and other spices including cinnamon, anise and cloves are water-hoggers too.

6. Bananas

Of all fruits and vegetables, bananas consume the most fertiliser: as much as half a tonne of nitrogen, phosphate and potash per hectare. We could feed more people by using these fertilisers on more efficient crops. For example, in Egypt farmers put almost 30 times as much nitrogen on their banana plantations as on the equivalent area of bean fields.

7. Chocolate

Another water guzzler. It requires around and the water footprint of cocoa powder is only slightly lower. For the same input, you could have 20 apples or 50 bowls of strawberries. If you are craving something sweet but are also concerned about feeding a growing human population, you know which to choose.