Australian researchers have taken investigations into obesity a step further to see why soon after overweight people lost weight, their metabolism slowed and they experienced hormonal changes that increased their appetites.
The researchers recruited healthy people who were either overweight or obese and put them on a strict diet that would lead them to lose 10 percent of their body weight. They then kept them on a diet for a year to maintain that weight loss. The researchers then found that the metabolism and hormone levels had not returned to the levels they where before the study started.
Obesity researcher at Hammersmith Hospital in London - Dr. Stephen Bloom, quoted that the study needed to be repeated under more strict conditions, but continued to add, “It is showing something I believe in deeply ; it is very hard to lose weight, and the reason being, is that our hormones work against us.”
The study which took place at the University of Melbourne looked at the volunteers eating between just 500 - 550 calories a day and proved, their hormone levels changed in such a way that it increased their appetites, and made them hungrier than before they started the study.
The volunteers where then put on diets for a year that would help maintain their weight loss, however a year later the volunteers had gaining the weight back despite the maintenance diet, on average gaining back half of what they had lost.
Further study into this showed that the hormone leptin, tells the brain how much body fat is present. When leptin falls, the volunteers appetite increased and their metabolism slowed down. A year after the weight loss diet, the hormone levels were still one-third lower than they were at the start, and leptin levels had increased as volunteers gained the weight back.
The results show Dr. Leibel quoted, that weight loss “is not a neutral event,” and that isn’t an accident when more than 90 percent of people who have lost weight put it back on. “You are putting your body into a circumstance it will resist,” he quoted. “You are, in a sense, more metabolically normal when you are at a higher body weight.”
