The case for cutting meat consumption has never been more compelling. Yet we remain stubbornly addicted to big protein hits in animal form. Could that be about to change?

If you share the typical British appetite, you will have worked your way through more than 1.5kg of meat this week as part of your annual 80kg quota of flesh-eating. That leaves you behind your typical American counterpart – working his or her way to 125kg a year – but still near the top of the international league of carnivores.

The case for cutting our meat consumption has long been a compelling one from whichever perspective you look at it – human health, environmental good, animal welfare, fair distribution of planetary resources. But it has never been a popular idea. The number of people in this country claiming to be vegetarian or partly vegetarian has stayed stable over the last decade, at around 4.8m. We remain culturally programmed to desire big protein hits in animal form. But could that be about to change?

Meat-reducing, as the marketers have branded it, may just have acquired fresh momentum. Self-confessed king carnivore Hugh Fearnley-Whittingstall has switched from meat to vegetables as his latest celebrity cause. Food inflation is adding its own deterrent effect, with supermarkets unwittingly bolstering consumers' ethical resolve by increasing the price of minced beef 25% in the last month as soaring commodity values hit the cost of animal feed. Meat substitutes, such as the fungus-derived protein Quorn, appear to be flourishing too, with sales up 9% in the last three months.

The two most pressing reasons for cutting back on meat today are climate change and global population growth. The post-war years have seen an explosion in the numbers of animals intensively reared for meat and milk. This livestock revolution, and the change in land use that has gone with it, however, now contribute nearly one fifth of global greenhouse gas emissions.

Most people could do more for the climate by cutting meat than giving up their car and plane journeys.

The UN predicts that the number of farm animals will double by 2050. Except, of course, it can't. If people in emerging economies start eating as much meat as we do, there simply won't be enough planet.

Intensive meat production is a very inefficient way of feeding the world. Farm a decent acre with cattle and you can produce about 20lbs of beef protein. Give the same acre over to wheat and you can produce 138lbs of protein for human consumption. If the grain that is currently used to feed animals were fed instead directly to people, there may be just enough food to go round when population peaks.

Replacing meat with more plant foods would also reduce diet-related diseases such as obesity, heart disease, and some cancers, according to reports in the Lancet. Malthusian panics about how to feed the world are not new, but the question has added urgency now as available resources dwindle. Nor is it the first time the problem has been framed in terms of meat. In 1970 Frances Moore Lappé published the seminal book Diet for a Small Planet, arguing that the American meat-centred diet was shockingly wasteful of protein.

Her recipe book to accompany it was full of ideas for less resource-intensive sources of complete protein, from bean burgers to wheat-soy varnishkas and peanut butter protein sandwiches.

The received wisdom at the time was that meat was superior because it contains "complete" protein with all the amino acids humans need for growth and maintenance. This hangup about complete protein seems to be one of the reasons meat still holds its powerful attraction. Until recently it was thought that we needed to eat the eight amino acids we cannot synthesise ourselves in combinations at the same time to be able to make use of plant protein. In fact nutritional science has subsequently caught up with the wisdom distilled in peasant cuisines that depend on beans and grains, and found this not true. But this idea of complete protein being the master ingredient persists, and is used to sell meat alternatives. Quorn is marketed as "a high quality meat-free protein. It has all the essential amino acids you'd find in other proteins like beef or chicken."

Quorn emerged from a search for new kinds of food in the early 1960s, when experts were predicting the world would run out of proteins to feed its growing population within two decades. Researchers at the bakery giant Rank Hovis McDougall (RHM) isolated a fungus in the soil in fields near its Marlow factory that could be fermented to produce protein. Imperial Chemical Industries (ICI), meanwhile, had developed techniques for mass production of bacterial single-cell proteins for its animal feed, Pruteen. In the early 1980s the two companies set up a joint venture with a grant from the Department for Trade to produce protein from the fungus for human food. The fungus was fed on glucose from wheat or maize in a fermenter for several hours where it multiplied, and was then filtered to yield fungal fibres which were rolled and frozen to create a mat with a chewy texture. Flavourings and egg albumen were added to bind it and "mycoprotein" was born. "Myco" comes from the Greek for fungus. It was approved by regulators for sale in the UK in 1985, then in the US in 2002, and is now marketed in 10 different countries.

The gospel of protein, as Geoffrey Cannon, editor of World Nutrition describes it, has been preached by governments for more than 100 years for three reasons: "power, empire and war". Protein became the master nutrient because concentrated animal protein promotes growth in early life. "This was a period when the most powerful European nations and then the USA were expanding their empires and preparing for mass wars fought by land armies. Growth in every sense was the prevailing ideology. Governments needed production of more, bigger, faster-growing plants, animals and humans."

American soldiers reared on diets high in meat and milk from the Midwest came over to help win the war in Europe in 1917 and in 1941 and seemed to be like young gods because they were so tall, broad and strong, even though their parents might have been smaller immigrant peasants from Europe. The physical weakness of the poorly-fed working classes in Europe was seen as an impediment to national growth. Increasing production and consumption of animal protein was a British national priority up to the second world war, Cannon explains.

Meanwhile, over in Germany in 1938, the German army high command was testing out its new Wehrmacht cookbook. "The soldier's efficiency can be maintained only if the elements consumed in working are supplied through the diet. The body is continually using up its own substance which has to be replaced in the form of protein, the body-building material," it declares. It had come up with the rather forward-thinking idea that reducing animal products would be more economically efficient, "as these products must be manufactured in a round about way from plant materials by the bodies of animals themselves. This is an extravagant use of food". Moreover, stocks of meat would be hard to accumulate and transport by the invading army. So instead the Germans tested mass feeding with protein from "pure soya". The infantry were given 150g a day of protein, with soya stuffed into everything possible, from liver noodles to goulash with brown gravy and sponge pudding with chocolate sauce, topped by rice and soya milk as a midnight snack.

Today's official guidelines are that adult men need just about one third of that Aryan-building calculation for protein. But recommended daily amounts of protein remain a somewhat movable feast. They depend on body weight, and have been adjusted as understanding has increased. What is clear, though, is that protein deficiencies are rare in developed countries and most of us, including vegetarians, eat much more than we need.

Joe Millward, professor of nutrition at Surrey University, has sat on several national and international expert committees that have drawn up recommendations on protein requirements. Vegetarians who eat eggs and milk "have no nutritional issues at all," he says. Their protein intakes are not much lower than the average meat eater's, and they get plenty of the micronutrients associated with meat, such as B12 and iron.

Dr Mike Rayner, director of the British Heart Foundation health promotion group, points out, in the book The Meat Crisis, that the average person in the UK is already getting about 31g a day of protein from cereals, fruit, nuts and vegetables including potatoes. The UK government estimates that the average woman needs 36g of protein per day and the average man 44g. "If official recommendations are right, then we don't need to eat much more of these foods to meet them."

Most people in this country and the US eat double the amount of protein they need. Excess is just broken down in the body for energy or stored as fat.

So if we don't need the protein, why not dispense with both the meat and the meat substitutes? Many Quorn consumers buy it because they want to lose weight, because it's convenient, or because they think it is healthier than meat, according to its manufacturers.

While many people clearly enjoy eating it, it is not without critics. The not-for-profit food safety campaign group in the US, Center for Science in the Public Interest (CSPI), has raised concerns about its potential to provoke allergenic and other adverse reactions in some consumers.

The manufacturers acknowledge that some people can have adverse reactions, but insist the numbers are very low. They quote a figure from the Food Standards Agency of between one in 100,000 and 200,000 being affected. That compares to about one in 300 thought to be adversely affected by soya protein.

"All protein foods have the potential to cause an adverse reaction in some consumers. The level of intolerance of Quorn products is extremely low and much lower than for other protein foods such as soya, nuts, shellfish, dairy and eggs," the company said in a statement, adding that its "products have been extensively tested and approved as safe by the relevant regulator in each market in which it is sold".

The FSA admitted that its figures for adverse reactions are based on data from the manufacturers themselves. It is extremely difficult to assess the prevalence of allergic reactions generally – there is no formal system for registering them, nor is there any official monitoring of allergic reactions to novel foods once they have been approved.

CSPI director Mike Jacobson says it has received reports from more than 1,000 people in the UK who say they have been made sick by eating the mycoprotein. In some cases the reaction was severe, and in a few, he says, even life-threatening, as consumers went into anaphylactic shock. The CPSI subsequently commissioned an independent poll of 1,000 UK consumers. "Four per cent of those who consumed Quorn said they were sensitive to it. That's a higher percentage than soya," according to Jacobson.

The regulator thought it unlikely levels would be that high without more reports appearing in the medical literature, but agreed there could be some underreporting.

Quorn says it convened a panel of independent allergy specialists and toxicologists in January who were paid an honorarium to review the safety of mycoprotein. They did not look at CSPI's case reports but concluded on the basis of peer-reviewed published studies that it was safe, Quorn Foods said. Neither its findings nor the experts' declaration of interests, nor the CSPI survey have yet been published.

For Hugh Fearnley-Whittingstall, it's an issue we should simply sidestep. "I'm not so much interested in replacing meat as ignoring it," he says.

Giving up meat 1970s-style

Diet for a Small Planet (Ballantine Books) offered dozens of recipes using "complementary proteins" from plant sources – including these wheat-soy varnishkas. The book's aim was to persuade people to cut down on meat.

4 servings, average serving = approx 11g usable protein, 26-31% of daily protein allowance.

• Have ready 1 cup macaroni, cooked and drained.

• Saute and set aside ¼ to 1/2lb mushrooms, sliced, and 1 large onion, chopped.

• Turn off heat and in same skillet mix until coated:

• ¼ cup soy grits

• ¾ cup bulgar or buckwheat groats.

• 1 beaten egg.

• Toast over medium heat, stirring constantly until dry. Pour over grain 2 cups of stock. Cover tightly, lower heat and cook for 10 mins.

• When cooked, toss with onion and mushrooms, cooked macaroni, 1 tbsp butter, and plenty of salt and pepper.

• This article was amended on 22 September 2011 and 9 November 2011. The original headline said: "Is it time we all gave up meat?" This has been clarified. In addition, the original stated: "The livestock of Europe already require an area of vegetation seven times the size of Europe to keep them in feed." This inaccurate comparison has been removed.