Many of us have heard that reducing calories delays aging and improves our metabolism but a recent study has shown that reducing protein and increasing carbohydrates has the same benefit. An animal study conducted at the University of Sydney showed that mice got the same benefits from a low protein and high carbohydrate diet as they did from a diet with a 40% reduction in calories. Reducing calories by up to 50% in us humans is unsustainable except for a very small dedicated minority – and you’ve probably seen them on TV in programmes presented by well-known characters such as Louis Theroux or Dr Michael Moseley.
Once the researchers discovered this finding in mice, they then went on to test different protein to carbohydrate ratios for weight gain and metabolic health, and used two scenarios: one where calories were restricted and another where food was freely available. Despite food being freely available, mice given higher carbs to protein ratio had a higher metabolism and did not gain weight.
The reason this study is so important is that we have become obsessed by lambasting carbohydrates, so now it’s time to look at the types of proteins and types of carbohydrates that can affect our metabolic health and whether these findings can be replicated in humans. Researchers are fairly confident about the problem with added sugars in food, the World Health Organisation only recently advised that the recommendation for daily consumption of added sugars be reduced down to 5% or our daily energy intake, but carbohydrates will always be the mainstay of our diet – around 50% of it! We need carbohydrates since they are the source of vitamins, minerals and dietary fibre (vegetables, fruits, whole grains, pulses, nuts and seeds) so I welcome a study that shows carbohydrates are not bad and should not be demonised. We just need to choose the right ones.
For now? Stick with this ratio: 15-20% protein, 45-55% carbohydrates, 25-30% (unsaturated) fat. Or, to put it visually, your daily food intake should have proportions roughly to this image: 
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Seb is a writer and blogger of food and nutrition. He holds a bachelors and a masters degree in nutrition science, and has studied sports and exercise nutrition at postgraduate level. He specialises in plant-based nutrition and believes passionately that we can all live with a little less meat.
