Anyone who has had to loosen their belt after enjoying a big meal may be reassured to know their weight gain was not in their imagination, as scientists find fat reaches the waistline as little as three hours after a big meal.
Researchers at Oxford University have discovered the fat in foods can be converted into tissue around the plumpest parts of the body within hours.
For a large meal containing 30g of fat, two to three teaspoons of the substance can be added to waists much quicker than previously thought.
If one continues to overeat, the fat will also be moved into tissue around the hips, rear and thighs for storage.
The study, by Fredrik Karpe and Keith Frayne, found the first fat from any meal enters the blood around an hour after being ingested.
By the time three or four hours has passed, they found, most of it had been incorporated into the adipose tissue, much of which lies in the short-term fat stores in the waist.
The results, which may require the adaptation the clichéd adage “a moment on the lips, a lifetime on the hips”, have resulted in a greater understanding of how weight gain works.
Previously, many have believed the process is much more gradual with food travelling from the gut into the blood, where is was used by muscles, with any excess being stored as fat.
But the Oxford University research suggests the fat is instead moved quickly around the body in the bloodstream before being “caught” and stored.
Karpe, professor of metabolic medicine, said: “The process is very fast. The cells in the adipose tissue around the waist catch the fat droplets as the blood carries them and incorporates them into the cells for storage.
“If you eat too much, you don’t get into this phase of starting to mobilise it. There will just be constant accumulation and you will start to put on weight.”
In a paper published in the Physiological Reviews, the scientists also suggested fit people found it easier to get rid of unwanted fat, as exercise gives a long-term boost to fat-burning mechanisms.
The results of the research come just days after British researchers advised people should use their waist measurements to determine the risk of suffering weight-related problems.
Dr Margaret Ashwell told the European Congress on Obesity in Lyon, France, that keeping waist circumference to half one’s height would help increase life expectancy.