To prevent obesity, should you eat like a pig?

You may not believe it, but some scientists suggest that you "learn to lose weight from pigs."

In March 2023, researchers from the United States and Canada published a paper in the journal Metabolites, "To Fight Obesity, Eat Like a Pig."

Scientists said seriously that pigs are "very suitable" subjects for obesity research . Pigs often eat very healthy and balanced food. Moreover, pigs have developed a "natural eating method that conforms to the biological clock and is not easy to gain weight", while humans have unfortunately lost this instinct.

Pigs, excellent research subjects

When we mention pigs, we think of fat. Although pigs are indeed very suitable subjects for obesity research, it is not because they are fat.

In fact, the average body fat percentage of pigs nowadays is at the level where you can see abdominal muscles in humans. The reason why pigs are getting thinner and humans are getting fatter is mainly because humans love to eat lean meat, so there are more and more lean pigs in the farms now.

A study has accurately measured the body fat percentage of 48 pigs and found that the average body fat percentage of pigs is 17.8%, ranging from 9.3% to 24.3%. This value is even lower than the body fat percentage of many humans . The body fat percentage of men is generally 12% to 20%, and the body fat percentage of women is generally 21% to 30%.

Human body fat percentage diagram | www.topendsports.com/testing/tests/bodyfat-visual.htm

Pigs are suitable for obesity-related research. The real reasons are as follows:

1

Pig Humanoid

The physiological mechanisms/digestive tract structures/digestibility coefficients/metabolic pathways of pigs and humans are very similar.

Like humans, pigs are omnivorous animals. In the wild, pigs, like us, often eat the roots, stems, leaves, fruits, eggs, insects, honey, and if there is meat, they will happily eat it.

Pig insulin was once used to treat type 1 diabetes in humans. Digestive enzymes extracted from pig pancreases were once used to treat pancreatic insufficiency in humans. Transgenic pig organs may be transplanted to humans in the future to treat human organ failure.

2

More importantly, Zhuzhu’s data is very reliable!

Pigs can be used for large-scale research. The pig farm can have as many pigs as needed. The pigs' diet can be strictly controlled, and they will never add extra food on their own.

It is difficult to convince humans to eat boring healthy food. Especially over time, when friends are eating barbecue and drinking milk tea, it is difficult for humans not to go beyond the limit. Pigs will not deceive researchers and say they did not eat after eating.

In contrast, when humans report their diets, they often omit items that scientists might get angry about.

In short, the data of pigs can serve as a good reference for humans.

How do pigs eat?

1

Pay attention to your body’s natural signals

One of the significant differences between pigs and humans is "when to eat". Compared with pigs, the time for humans to eat seems a bit "inappropriate".

Human eating is often driven by emotions, and we tend to eat at times that are “socially appropriate” and “convenient to get food.” In contrast, pigs try to eat at times that are in line with their physiological needs, and insulin, melatonin, and cortisol may be the driving factors. (Humans may have lost this instinct.) Pigs don’t like to eat a lot of meals at one time, and prefer to eat smaller meals, such as 5 to 6 meals a day.

Analysis shows that eating small and frequent meals like this will keep the pigs' blood sugar more stable and less likely to trigger glucose conversion into fat . In this way, even if the total calories remain unchanged, the pigs are less likely to gain weight and have more developed muscles.

Pigs naturally like to eat breakfast and dinner, and usually eat the most dinner between 19:00 and 20:00.

The natural feeding curve of pigs at different times of the day | Paper

Pigs are the least likely to gain weight if they eat according to this natural rhythm.

However, once this eating pattern is deviated, pigs tend to gain weight. Once, scientists forced piglets to change their meal time by 12 hours. As a result, the piglets' physical activity decreased by 7% and their fat increased by 7%. The conclusion is that for pigs, the calories eaten between 19:00 and 20:00 are not easy to be converted into fat, but if the same calories are eaten at midnight, they will become fat. (A horse will not gain weight without wild grass, and a pig will not gain weight without midnight snacks.)

Another situation is that low status leads to the inability to " eat according to natural rhythms ". If pigs are raised in groups, then high-status pigs can eat whenever they want, so they can eat according to natural rhythms. But low-status pigs are not so lucky. They need to wait until the high-status pigs have finished eating before they can eat. Therefore, they do not eat enough during the "natural peak feeding period" and can only eat more at other times to compensate.

Copyright images in the gallery. Reprinting and using them may lead to copyright disputes.

The result was that low-status pigs were more likely to become obese , which fits with the "insurance hypothesis" of obesity, that is, "the lack of food security is a driving factor in obesity."

Since there is no guarantee that you can "eat whenever you want" and you can only "eat when you can", the dietary pattern and endocrine pattern cannot be coordinated, which leads to obesity.

In terms of taste, research on the "palatability" of pig food shows that pigs, like humans, like to eat unhealthy sweets, that is, foods with a high insulin index. However, breeders will consider nutrition, so pigs are usually forced to eat more vegetables, whole grains, and beans. These foods are digested slowly, blood sugar will not soar quickly, and it is easier to grow lean meat.

Research has found that pigs don't like to eat healthy food, but when they are only given healthy food, they will eat it . Even if the feeding time is not right, pigs still don't get fat. Why? It may be because the nutrition of pig food is very balanced, which can be said to be an excellent healthy and balanced diet.

2

Innate genetic influence is significant

Not every pig has a physique that is "easy to gain fat". For example, Pietrain pigs are lean pigs that look like they work out in the gym every day (← original words from the paper). Meishan pigs (native to China, a group of Taihu pigs) are fat pigs that look like fat guys on the sofa (← original words from the paper).

Lean pigs vs. fat pigs | Wiki

The difference between the two types of pigs lies mainly in how much muscle they have and how they use energy.

Lean pigs usually reach sexual maturity later, have a stronger ability to grow muscle, have less fat, and lose heat easily in a cold environment. In contrast, fat pigs usually reach sexual maturity earlier, have a weaker ability to grow muscle, have fat to keep warm in a cold environment, and do not lose heat easily.

Lean pigs have higher requirements for feed. In order to achieve rapid muscle growth, they usually need a high-protein, low-carb feed (← doesn’t it sound like what your fitness trainer tells you to eat to gain muscle?).

In the past, our country liked to raise fat pigs. Fat pigs have another advantage - they can tolerate roughage. They can eat anything and grow fat. The body fat percentage of such pigs is not necessarily lower than that of humans.

3

Acquired experiences also affect

If pigs encounter adversity such as hypoxia and malnutrition during the fetal stage or infancy, they will become " prone to obesity ". These pigs have insulin resistance similar to type 2 diabetes. These pigs are insensitive to insulin, which causes insulin to not work properly. From a molecular mechanism perspective, this belongs to "epigenetic programming". Acquired experiences can regulate the expression of innate genes.

For humans, people who have experienced famine during their fetal and childhood periods are more likely to suffer from type 2 diabetes and obesity. However, one thing that is very impressive about pigs is that although they have become "prone to obesity", in reality, not many pigs actually become severely obese.

The study found that these insulin-resistant pigs seem to be able to sense changes in their blood sugar . If they eat a normal diet, these pigs will automatically control their food intake and eat less. But if they eat a "diabetic healthy diet" with a "low glycemic index", these pigs will eat more! And when they eat a "diabetic healthy diet", they grow as fast as other pigs. (In contrast, humans have lost this ability to "sense whether a diet will cause high blood sugar.")

Another important event that pigs encounter is castration. Castrated pigs...eat more. To maintain the same weight, castrated male pigs need to eat the most, followed by intact female pigs, and intact male pigs eat the least.

In other words, for pigs, while losing certain worldly desires, they also lose the ability to keep the pork on their bodies.

4

To grow muscles, balanced nutrition is very important

The study also found that it is really difficult for pigs to grow muscles, but it is too easy to grow fat. The conversion of food into fat seems to be the "easiest pathway".

To convert food into muscle, pig feed needs to be nutritionally balanced, with adequate amino acids, minerals, B vitamins, phosphates and other micronutrients.

Phosphate is an important but often overlooked nutrient. If pigs eat starch but do not have enough phosphate, the starch will be easily converted into fat. When phosphate is sufficient, pigs will be more likely to convert calories into muscle rather than fat.

In one study, pigs were fed a diet that was high in phosphate (0.475%) and low in phosphate (0.08%). The phosphate-deficient group ate less, 4% less food, but had 17% to 21% more fat and 6% to 8% less total muscle mass.

Animals seem to be able to sense when they are lacking phosphates, and sometimes herbivores will start chewing bones just to get the phosphates.

Osteophagy in herbivores is often caused by a lack of phosphates | Thetford Private Game Reserve

The study also showed that (for pigs), there is no junk food, only junk diets. As long as the ratio is good and the nutrition is sufficient, the pigs will not be overweight. There is a study that let pigs eat pig feed made from "ultra-processed food".

An animal feed factory in the Netherlands has collected a large amount of discarded human food - biscuits, caramels, bread, marshmallows, cream...all things that look fattening.

However, when these things were used as raw materials and sufficient nutrients were added to the formulated pig feed, the pigs did not gain noticeable weight.

By the way, if pigs grow enough muscles, they won’t become prone to obesity.

In a pig, every 1 kcal of net energy consumed can synthesize 0.916 kcal of fat. If that 1 kcal of net energy is used to make protein, only 0.511 kcal of protein can be formed. And once fat is formed, it is not updated very often, lying quietly in the pig, consuming not much extra energy.

But after muscles are formed, protein needs to be constantly renewed, so energy needs to be continuously consumed.

5

Fructose may really be unhealthy

There are three major problems for pigs to eat fructose: first, the digestibility is low; second, it puts a burden on the liver; and third, it induces obesity.

Fructose exists naturally in fruits and honey, but in recent years, it has appeared in large quantities in processed foods and sweetened beverages. The reason is that humans have discovered a way to produce large amounts of fructose syrup from corn, and this extremely cheap sugar has taken over the market.

High fructose corn syrup appears in large quantities in processed foods and sweetened beverages | Photo by the editor

Then humans started to gain weight like crazy - of course there are other multiple factors, but fructose definitely contributes.

Fructose is metabolized in the liver, and a lot of phosphates are consumed during the metabolism. The fat produced is easily accumulated in the liver, leading to fatty liver.

In terms of digestion, studies on pigs have found that the intestines of piglets can absorb 98.3% of sucrose and 98.3% of glucose, but only 86.6% of fructose. In addition, fructose may cause diarrhea in piglets. For humans, there may be a similar situation. Some humans may not be able to absorb and digest fructose well.

There is a "fructose wintering hypothesis" that holds that fructose-induced fat was once beneficial to survival. In the past, fructose appeared in fruits in autumn. At this time, wild animals ate high-fructose foods, which induced fatness and stored a lot of fat on their bodies to build energy buffers and reserves, so that they could survive the cold winter when food was scarce.

The problem is that the unlimited supply of fructose all year round has made the body "survive the winter every day."

6

Fat, pigs grow what they eat

Pigs have a distinct characteristic when it comes to fat - they grow the same fat as what they eat . Basically, if pigs eat saturated fat, they grow saturated fat; if they eat unsaturated fat, they grow unsaturated fat. This actually brings some troubles to the pig farming industry.

Saturated fats are solid at room temperature, while unsaturated fats are liquid at room temperature. Some pig farmers mix unsaturated fats such as mayonnaise into their pig feed, and as a result, the pigs also grow a lot of unsaturated fats. As a result, the pork becomes difficult to slice - because some fats are liquid at room temperature.

In recent years, people have been eating more and more unsaturated fat. One guess is that this makes the fat in people's bodies more unsaturated and more "fluid". Under the action of gravity, excess fat on the body is easy to sag, making it easier to look older.

Summary of Pig's Weight Loss Experience

The weight loss enlightenment that Pig Pig brings to us can be summarized as follows:

① You don’t have to go to work and can eat according to your body’s physiological rhythm, which makes it less likely to gain weight.

②Balanced nutrition will make you less likely to gain weight. Lack of micronutrients such as phosphate will make you more likely to gain weight.

③ After experiencing famine (including excessive dieting), the body is more likely to gain fat.

④ Eat less fructose.

⑤ The total amount of calories consumed is very important. Controlling the calories in pig feed can regulate the weight changes of pigs very accurately. The same is probably true for humans.

References

[1]van Kempen, TATG, & Zijlstra, RT (2023). Eat like a Pig to Combat Obesity. Metabolites, 13(3), 420. doi: 10.3390/metabo13030420

[2]Mitchell, AD, Conway, JM, & Potts, WJ (1996). Body composition analysis of pigs by dual-energy x-ray absorptiometry. Journal of Animal Science, 74(11), 2663. doi:10.2527/1996.74112663x

Planning and production

Source: Guokr (ID: Guokr42)

Author: You Shiyou, chief writer of Guokr.com, member of China Science Writers Association

Editor: Yinuo

Proofread by Xu Lai and Lin Lin

The cover image and the images in this article are from the copyright library

Reprinting may lead to copyright disputes