Eating habits and food production need to radically change in order to improve people's health and avoid potentially catastrophic damage to the planet, major new research has found.
The findings come from the EAT-Lancet Commission, a three-year project which brought together almost 40 worldwide experts in a number of fields including human health, agriculture and environmental sustainability.
The commission found that the world's food system needs urgent transformation because currently, more than three billion people are malnourished - this includes people who are undernourished and overnourished - and food production is driving climate change, pollution, the loss of biodiversity and unsustainable changes in land and water use.
It emphasises that feeding an increasing population of 10 billion people by 2050 with a healthy and sustainable diet will simply not be possible if eating habits are not transformed and food production is not improved.
The commission recommends a diet high in plant-based foods, such as fruit, vegetables, nuts and legumes and low in animal-based foods, refined grains, highly processed foods and added sugars.
Based on a diet of 2,500 k/cal per day, people should be consuming around 500g of fruit and vegetables every day, and no more than 14g of red meat, which is equivalent to a half a rasher of bacon. A typical pork chop or sirloin steak usually weight at least 200g.
It recommends 232g of whole grains per day, such as rice and wheat, 50g of starchy vegetables such as potatoes, and 250g of dairy, such as whole milk and cheese.
It also recommends just 29g per day of poultry, 28g of fish and 13g of eggs, which is equivalent to one-and-a-half eggs per week. A typical chicken fillet weighs approximately 160g.
The commission warns that the way people eat is inextricably linked to health and environmental sustainability, and both are now at major risk.
It points out that unhealthy diets are the leading cause of ill health globally and following this healthier diet could lead to 11 million fewer premature deaths every year. Meanwhile the way in which food is produced needs to change and food waste must be reduced.
The commission emphasised that unprecedented global collaboration and commitment will be needed if this is to succeed.
"The food we eat and how we produce it determines the health of people and the planet, and we are currently getting this seriously wrong. We need a significant overhaul, changing the global food system on a scale not seen before in ways appropriate to each country's circumstances. While this is unchartered policy territory and these problems are not easily fixed, this goal is within reach and there are opportunities to adapt international, local and business policies.
"The scientific targets we have devised for a healthy, sustainable diet are an important foundation which will underpin and drive this change," commented one of the commission authors, Prof Tim Lang, City, University of London in the UK.
Meanwhile, according to co-lead commissioner, Dr Walter Willett of Harvard University in the US, the world's diets ‘must change dramatically' in the coming years.
"More than 800 million people have insufficient food, while many more consume an unhealthy diet that contributes to premature death and disease. To be healthy, diets must have an appropriate calorie intake and consist of a variety of plant-based foods, low amounts of animal-based foods, unsaturated rather than saturated fats, and few refined grains, highly processed foods, and added sugars.
"The food group intake ranges that we suggest allow flexibility to accommodate various food types, agricultural systems, cultural traditions, and individual dietary preferences - including numerous omnivore, vegetarian, and vegan diets," he said.
Details of the commission's findings are published in the journal, The Lancet, and can be viewed here