Over the years pigs have had a bad press. They have been accused of being greedy, lazy and fat so often that phrases like "greedy pig" are part of everyday language.

In fairness, pigs can be a greedy lot. As a student I worked on a pig farm in Norfolk where you had to be nimble and fleet-of-foot at feeding time. There were 500 sows running outdoors on a free-range system, that were mostly kept in batches of twenty in paddocks that also contained pig arks for shelter.

Those sows were fed compressed lumps of feed, called rolls, on the ground. At feeding time, you opened a bag containing 25kg of rolls, put it on your shoulder, opened the gate into the paddock, and then somehow sprinted through the bunch of hungry sows that had congregated there, sprinkling a line of rolls on the ground as you ran. Easier said than done.

Invariably you slipped or tripped over a sow and would then be trampled under-hoof by twenty greedy sows devouring the contents of the bag.

Even the way pigs feed sounds greedy. They chomp and slurp at such a rate that everything is gobbled up in a few minutes.

Pigs have a digestive system similar to ours. Ruminants, like cattle and sheep, eat large volumes of grass and need to graze for hours on end, so they are constantly on the move. Once a pig has gulped down its meal it can literally laze about till the next feeding time - and pigs are good at lazing about.

They lie flat for hours on end, occasionally grunting with contentment. Best of all, they love to wallow in a muddy hole on a hot day. Greedy appetites and laziness can lead to pigs becoming very fat. That was important in the days when people liked to eat roast pork with a good covering of fat, or streaky bacon. Fashions change and modern consumers prefer lean meat. In response to changing market demand, farmers have bred leaner strains of pigs.

According to researchers at the Agriculture and Horticulture Development Board (AHDB), British pigs are now 44 per cent leaner than they were in the 1970s.

However, according to AHDB, many people still have an outdated view of pork. A survey revealed that 52 per cent of British people thought a pork medallion contained more saturated fat than a skinless chicken breast. In fact, pork medallions contain on average just 0.17g of saturated fat per 100g compared to a skinless chicken breast, which contains on average 0.2g per 100g.

I remember about twenty years ago that researchers at the University of Wales had reckoned that modern diets and breeding programmes were producing pigs that developed symptoms similar to anorexia nervosa. While it only affected a few pigs, scientists reckoned the new disease was on the increase. One bonus of their research was that it helped them to understand human eating disorders. As I said, pigs have a similar digestive system to humans and are roughly the same body weight. So those thin pigs were used to test new drugs for treating anorexia.

Chinese researchers have gone even further and announced last autumn they had bred pigs with 24 per cent less fat than modern regular pigs. The experimental, "low-fat" pigs were genetically unique as they had mice proteins in their system.

Pigs don't carry the gene that produces brown fat - the stuff that helps most mammals stay warm when it's cold by burning fat. That's because they lack the requisite protein, known as UCP1, but the team from the Chinese Academy of Sciences found a way to build that protein into baby pigs.

The researchers in Beijing snipped a bit of the UCP1 mice protein into 2,553 cloned pig embryos using a gene-editing technology that's kind of like a cut-and-paste function for genetic code. Embryos were then implanted into thirteen pigs, three of which became pregnant, giving birth to twelve male pigs. Those animals were found to be completely healthy, and one even managed to mate and produce healthy offspring.

The new strain of pigs they created had brown fat that can keep them warmer, without putting on as much "white" fat - or lard as we know it. When the brown fat pigs were slaughtered at 6 months old they didn't weigh much less than normal pigs, but they had a higher ratio of lean meat on their bodies.

It all sounds very "Frankenstien" but don't be alarmed, these new pigs are unlikely to find their way into the human food chain anywhere in Europe.