Beware of skinny friends with big appetites

fat and thin peopleThin friends who eat a lot could put your waistline at risk, according to a new study in the Journal of Consumer Research, which examines how other peoples’ weight and food choices influence how much we eat.

“Obesity is obviously a tremendous public health concern,”

write authors Brent McFerran, Darren W. Dahl (both University of British Columbia), Gavan J. Fitzsimons (Duke University), and Andrea C. Morales (Arizona State University).

“We decided to investigate how someone’s size and food choices could influence how much the people around them eat.”

Researchers recruited 210 college students to participate in a study that was ostensibly about movie watching. The participants were told they would be paired with another student taking part in the study. The other student was actually a member of the research team whose natural build was thin (size 0, 105 pounds). But at times this same researcher donned an “obesity prosthesis,” which made her appear to be a size 16 and 180 pounds.

All of the students were offered snacks while viewing film clips. The undercover researcher was served first, and helped herself to either a large or small serving before the student participant was offered the same bowl of food. In all cases, the amount of food the students accepted was influenced by the portion size chosen by the undercover researcher, regardless of her size.

“Most participants took a portion similar to what the researcher served herself,” the authors explain. “However, it is clear that how much food each person took, and how much they ate depended on whether their companion was thin or obese.”

Participants tended to mimic the thin companion’s portion sizes. But when they presumed the researcher to be obese, the participants adjusted the amounts they ate.

“This indicates that people are influenced, even without being aware of it, by other people’s portion choices,” the authors write.

“Our findings indicate that the size of the person you dine with matters much less than the size of the meal they order,” the authors write. “If a heavy-set colleague eats a lot, you are likely to adjust your behaviour and eat less. But a thin friend who eats a lot may lead you to eat more than you normally would.”


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Modern chickens provide more energy from fat than protein

broiler chickensIn 1976, the Royal College of Physicians and the British Cardiac Society in a report on heart disease, recommended eating less fatty red meat and more poultry instead because it was lean. However, the situation has changed since then.

A new paper in the journal Public Health Nutrition describes analysis of chickens sold in 2004-2008 compared to historical data.

Samples were obtained randomly between 2004 and 2008 from UK supermarkets, farm shops and a football club. The amount of chicken fat was estimated by emulsification and chloroform/methanol extraction.

First the content of omega 3 DHA (docosahexaenoic acid) has fallen to less than a third of the value in 1970s. Secondly, the fat content of the chicken carcass has risen; now providing about three times the calories compared to protein. Such chickens are no longer a protein rich food but a fat rich food. Thirdly, the organic chickens we analysed were little better.

The explanation is simple; namely that they are fed largely on cereals and whether organic or not, the cereals contain little omega 3 fatty acids.

The value of the omega 3 DHA is that it is preferentially utilised for the brain and vital organs. Traditionally, chicken meat and hens eggs would have been valuable land sources of omega 3 DHA.

Fully free range chickens would get the omega 3 from the green foods (grass, leaves and small animals that eat plants). However, feed hoppers maintained full 24 hours a day with omega 3 deficient food destroys the incentive of the birds to search for such foods even if they are allowed out of doors.

In addition, the denial of exercise and again 24 hour availability of energy dense and omega 3 deficient food in the broiler system provides exactly the recipe for weight gain which means fat gain. Genetic selection for fast weight gain makes that situation worse. The biochemical analysis of the meat of the birds is not only consistent with the loss of omega 3 and increase in fat, but also the lack of exercise and the selection for fast weight gain which exacerbates the loss of omega 3.

As the omega 3 DHA is important for the brain, its growth and function, it is worth asking how much would it cost to get the same amount of DHA from a 1Kg chicken today. You would need to eat about 4 chickens at a cost of £12 which at the same time would be associated with 5,000 calories of fat. Not a good idea.

Many scientists consider that the rise in mental ill health is due to the loss of omega 3 fatty acids DHA and EPA in the diet.

The answer is to eat more plant-based foods, including nuts, seeds, whole grains and vegetables like avocado.

If you have not yet transitioned to a fully plant-based diet, you can replace chicken and beef in your diet with oily fish such as mackerel and sardines.

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Timing of meals may influence obesity

restaurant-sunsetA study conducted by Northwestern University published on 3 September in the journal Obesity has found that eating at irregular times – the equivalent of the middle of the night for humans, when the body wants to sleep – influences weight gain. The regulation of energy by the body’s circadian rhythms may play a significant role. This is one of the first pieces of scientific evidence linking meal timing and increased weight gain. 

“How or why a person gains weight is very complicated, but it clearly is not just calories in and calories out,” said Fred Turek, professor of neurobiology and physiology in the Weinberg College of Arts and Sciences and director of the Center for Sleep and Circadian Biology. “We think some factors are under circadian control. Better timing of meals, which would require a change in behaviour, could be a critical element in slowing the ever-increasing incidence of obesity.” 

The findings could have implications for developing strategies to combat obesity in humans, as more than 300 million adults worldwide are obese, including more than a third of American adults and a quarter of UK adults. 

“One of our research interests is shift workers, who tend to be overweight,” said lead author Deanna M. Arble, a doctoral student in Turek’s lab. “Their schedules force them to eat at times that conflict with their natural body rhythms. This was one piece of evidence that got us thinking — eating at the wrong time of day might be contributing to weight gain. So we started our investigation with this experiment.” 

Simply modifying the time of feeding alone can greatly affect body weight, the researchers found. Mice that were fed a high-fat diet during normal sleeping hours gained significantly more weight (a 48 percent weight increase over their baseline) than mice eating the same type and amount of food during naturally wakeful hours (a 20 percent increase over their baseline). There was no statistical difference between the two groups regarding caloric intake or the amount of activity. 

Over a period of six weeks, both groups of mice were allowed to eat as much high-fat diet as they wanted during their daily 12-hour feeding phase. Much like many humans, mice prefer high-fat food. Since mice are nocturnal, the 12-hour feeding phase was during the day for those fed during normal sleeping hours and during the night for those fed during naturally wakeful hours. Food was not provided during the other 12 hours of their day. 

Our circadian clock, or biological timing system, governs our daily cycles of feeding, activity and sleep, with respect to external dark and light cycles. Recent studies have found the body’s internal clock also regulates energy use, suggesting the timing of meals may matter in the balance between caloric intake and expenditure.

Please click here to learn more about the ideal time to eat. 

To learn more about Managing Your Weight Naturally, please come to a Cooking for Health Course, held throughout the year in Somerset, UK.