After being injected with an opiate-like chemical produced in the human brain, laboratory rats ate twice the normal amount of sweet fatty food. (Photo: Alexandra Difeliceantonio)

Are you on a diet but  having a hard time resisting that candy bar or cheeseburger?  The problem  might really be in your head.

Researchers have found that an opium-like chemical produced in the brain might explain why some people overeat sweet and fatty foods.

“This means that the brain has more extensive systems to make individuals want to over consume rewards than previously thought,” says Alexandra DiFeliceantonio of the University of Michigan, Ann Arbor, who led the study. “It may be one reason why over-consumption is a problem today.”

The researchers found  a region of the brain called the neostriatum, located near the middle and front of the brain, which is best known for  controlling motor movements. It also produces the opiate-like chemical called enkephalin, which  DiFeliceantonio says sparks and intensifies the urge to consume pleasant rewards.

To make their findings, DiFeliceantonio and her team injected some of the morphine-like drug directly into the neostriatum of their lab rats.  After the injections, the rats were fed candy-coated chocolate. The rodent test subjects ate more than twice the number of chocolates than they would normally have eaten.

The researchers also found the levels of enkephalin – the opium-like chemical manufactured by the neostriatum – surged when the rats began to eat the  candy. And while the enkephalins, or comparable drugs, didn’t actually make the rats enjoy the candy more, they did increase their cravings and compulsion to eat them.

“The same brain area we tested here is active when obese people see foods and when drug addicts see drug scenes,” says DiFeliceantonio. “It seems likely that our enkephalin findings in rats mean that this neurotransmitter may drive some forms of overconsumption and addiction in people.”

DiFeliceantonio says the findings  reveal a lot about our tendency to binge and could eventually lead to the development a drug that  blocks the impulse to overeat.

Turns out obesity isn’t just a health issue;  all of that overeating could seriously cut into the future world food supply.

According to a new study from Great Britain, if the current worldwide obesity epidemic continues unabated, maintaining enough food to feed the world could actually become a much more serious challenge.

Right now, the world’s population is over seven billion, and growing.  The more people there are, the more food and resources are needed.

According to the London School of Hygiene & Tropical Medicine,  the weight of the human population should be taken into consideration – in addition to the number of people in the world -  when determining future food security and environmental sustainability.

Using data from various studies, researchers determined the world’s adult population weighs 287 million metric tons, or 287 billion kilograms.

Separately, we each weigh an average of 62 kilograms, but that average varies from country to country.

Researchers estimate 15 million of that 287 metric tons is due to those who are overweight, while 3.5 million metric tons are due to obesity.

North Americans have the highest body mass of any continent, according to the study, with an average body mass of 80.7kg.

While North America has only about six percent of the world’s population, it contributes 34 percent of the world’s biomass.

Asians, on the other hand, whose average weight is 58 kilograms, make up around 61 percent of the world’s population, but they’re only responsible for roughly 13 percent of the world’s biomass.

Among nations,  the United States came in as the “heaviest” country, while Eritrea was the “lightest”.

The researchers also looked at how those who are overweight and obese impact the total weight and averages.

Keep in mind that there is a difference between being overweight and obese.

You’re considered to be overweight when you weigh more than the weight that is appropriate for your height and bone structure or have a Body Mass Index (BMI) of 25 or greater.

If you have BMI of 30 or more, medical experts consider you to be obese.

Experts say that up to half of all food that is eaten is burned up by various physical activities.  But as your weight rises, your energy requirements increase as well, because it takes more energy to move a heavy body.

Even when at rest, those who have a bigger body mass burn more energy.

So, the bigger you are, the more energy you’ll need; the more energy you need means you must eat more; the more food eaten by a growing world population could  then, in turn, impact affect food supplies and future food security.

Soybeans being harvested (Photo: Jake was here via Wikimedia Commons)

The domino effect of a heavier populace can also affect environmental sustainability.  Because in order to feed, cool or warm and transport a heavier population, more natural resources, such as fossil-fuels, will be needed and consumed.

Sarah Walpole, a practicing medical doctor who co-authored the study,  worries people from developing nations, who tend to be thinner than those in developed countries, will be most at risk of food insecurity.

“If our global consumption for food or our demand for food are increasing, it going to be those poor populations that feel the impact most,” she says.

One of the areas researchers want to study next is the impact the global child population has on the world’s total human biomass.

Dr. Walpole joins us on this week’s radio edition of “Science World.”  Check out the right column for scheduled air-times or listen to the interview with Dr. Walpole below.

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Other stories we cover on the “Science World” radio program this week include:

• Kenyan conservationists preserve endangered sea turtles
• Ocean levels rising faster on US coasts than elsewhere in the world
• 2009 swine flu deaths were much higher than first reported
• Crisis mapping helps first-responders do their jobs in times of disaster
• Gastric Bypass Surgery, Alcohol Not a Good Mix for Some