Tag Archives: overeating

Social isolation can lead to overeating and under-sleeping — if you’re a fruit fly

New research on fruit flies provides the first reliable animal model for studying our bodies’ reactions to loneliness.

Image credits Mohamed Nuzrath.

Social isolation; we’re all probably more intimately familiar with the term, given these past two years, than we’d like to be. But we’re not the only ones who suffer when we’re separated from our group. New research on fruit flies shows that they as well sleep too little and eat too much when deprived of social interactions. The paper also reports on changes in gene expression, neural activity, and behavior seen in the flies.

The findings are of interest to all of us today, as they point to novel ways of understanding the effects loneliness has on our bodies. They’re also relevant to scientists directly studying fruit flies, or those whose work involves fruit flies, as accounting for these effects would go a long way to improving the reliability of our conclusions.

Flyin’ solo

“Flies are wired to have a specific response to social isolation,” says corresponding author Michael W. Young, the Richard and Jeanne Fisher Professor and head of the Laboratory of Genetics at Rockefeller. “We found that loneliness has pathological consequences, connected to changes in a small group of neurons, and we’ve begun to understand what those neurons are doing.”

It’s not a stretch to say that most of us have had trouble maintaining our pre-lockdown sleep schedule. Many of us are also overeating, or eating at odd hours, and have gained weight. The team behind this study suspected that the social isolation brought about by the lockdown is, in itself, to blame for this. It seems like their hypothesis panned out, as the results describe how chronic separation from the group can have measurable effects on the body (at least in fruit flies). These effects include changes in gene expression, neural activity, and behavior.

Fruit flies (Drosophila melanogaster) are a very social species. They forage and eat in groups, have complex mating rituals, and even engage in some tiny fights from time to time. However, they spend most of their time (up to 16 hours each day) sleeping — also in groups. They have long been a model organism for researchers in various fields of biology. So, when the team turned to them to test their hypothesis.

“Over and over again, Drosophila have put us on the right track,” says Young. “Evolution packed a great deal of complexity into these insects long ago and, when we dig into their systems, we often find the rudiments of something that is also manifest in mammals and humans.”

“When we have no roadmap, the fruit fly becomes our roadmap,” adds lead author Wanhe Li.

The team first compared how fruit flies behave under various lockdown conditions. Flies were kept together in groups of various sizes, ranging from several individuals to a single fly, for a week. For the most part, the insects didn’t have any problems; even flies who were kept with a single other fly didn’t show any distress. However, those that were entirely isolated from their peers started sleeping less and eating more as the trial progressed.

The team further reports finding changes in the expression patterns of a constellation of genes linked to starvation in the brains of these lonely flies. This, they argue, is the genetic link between social isolation and the observed biological changes. One group of cells known as P2 neurons were involved in changing the flies’ feeding and resting behavior. When the P2 neurons were disabled in chronically-isolated flies, they reverted to more normal feeding and sleeping patterns. Amplifying their activity in flies that were only isolated for one day caused them to exhibit the sleeping and overfeeding behavioral patterns of flies who had been isolated for a full week.

“We managed to trick the fly into thinking that it had been chronically isolated,” says Wanhe Li. “The P2 neurons seem to be linked to the perception of the duration of social isolation, or the intensiveness of loneliness, like a timer counting down how long the fly has been alone.”

While these findings haven’t been replicated in humans, the team is confident that more or less the same biological mechanisms seen in these flies operate in isolated humans as well. It’s not the same as confirming that people who ate more and slept less during the lockdown did so because of their P2 neurons — but it’s a starting point, at least.

“Clinically-oriented studies suggest that a large number of adults in the United States experienced significant weight gains and loss of sleep throughout the past year of isolation precautions due to COVID-19,” Young says. “It may well be that our little flies are mimicking the behaviors of humans living under pandemic conditions for shared biological reasons.”

The paper “Chronic social isolation signals starvation and reduces sleep in Drosophila” has been published in the journal Nature.

A fifth of the world’s food is lost to waste and over-eating

Credit: Food Navigator.

An extensive analysis of the world’s global food supply found we’re losing more food to waste and overconsumption than previously believed. We eat 10 percent more food than we need — obviously, some parts of the world consume far more than this average figure since 780 million are suffering from chronic undernourishment at the same time.  Additionally, 9 percent of all the food we make goes to waste or spoils.

The study was conducted by Scottish researchers at the University of Edinburgh using data collected by UN’s Food and Agriculture Organization. This kind of quantitative analysis at every stage of food production is extremely important if we’re to meet the demands of a growing population sustainably.

The good news is we’re making enough food for everyone. The bad news is we’re quite terrible at distributing food and making it efficiently.

Food system losses were considered in six categories, as follows:

  1. Agricultural production: losses that occur in the production process. The losses include agricultural residues (e.g. roots and straw), unharvested crops and the losses during harvest.
  2. Livestock production: losses and inefficiencies in the conversion of feed and grass into animal products.
  3. Handling, storage, and transportation: losses due to spillage and degradation during storage and distribution. These losses occur for primary crops, processed commodities, and animal products.
  4. Processing: losses during the processing of commodities.
  5. Consumer waste: losses and waste between food reaching the consumer and being eaten.
  6. Over-consumption: the additional food intake over that required for human nutrition.

According to the Edinburgh researchers, half of the crops we grow — that’s 2.1 billion tonnes — are lost to over-consumption, consumer waste, and inefficiencies in production. The results suggest that due to cumulative losses, the proportion of global agricultural dry biomass consumed as food is just 6% (9.0% for energy and 7.6% for protein), and 24.8% of harvest biomass (31.9% for energy and 27.8% for protein), the researchers wrote. But the most inefficient food production process is growing livestock, with losses of 78 percent or 840 million tonnes. About 40 percent of all losses of harvested crops can be attributed to livestock breeding which requires an immense amount of animal feed and water. Some 1.08 billion tonnes of harvested crops are used to produce 240 million tonnes of edible animal products including meat, milk and eggs.

“The results here suggest that system losses from over-consumption of food are at least as substantial as the losses from food discarded by consumers (Fig. 4), and therefore have comparable food security and sustainability implications. Consequently, greater research focus may be required to better understand causes, effects and solutions for over-consumption,” the researchers said.

Globally, 14.5% of greenhouse gas emissions come from the rearing and butchering of cows, chickens, pigs and other animals – more than the emissions from the entire transport sector. That’s because animals release methane, a highly potent greenhouse gas, while crops release carbon through land clearing and fertilizer use.

Bearing these stats in mind, an increase in consumption of meat and dairy products would disproportionately put more strain on the global food supply. This is a serious concern for the coming decades as more and more people in developing countries, from China to India, are improving their financial condition. In 1982, the average Chinese person ate just 13kg of meat a year. Beef used to be called the ‘millionaire’s meat’. Now, the average Chinese eats 63kg of meat a year and could consume 30kg more by 2030.

The researchers recommend in Agricultural Systems that people should eat fewer animal products. As we reported earlier, lower meat consumption would cut food-related emissions by 29%, vegetarian diets by 63%, and vegan diets by 70%. Reducing waste and being careful not to exceed your nutritional needs should also be a priority.

“Reducing losses from the global food system would improve food security and help prevent environmental harm. Until now, it was not known how over-eating impacts on the system. Not only is it harmful to health, we found that over-eating is bad for the environment and impairs food security,” said Dr. Peter Alexander, of the University of Edinburgh’s School of GeoSciences and Scotland’s Rural College, who led the study.



Last supper paintings shows biblical growth of portions

According to a research conducted by researchers from the Cornell University the portions and the plates depicted in more than 50 paintings of the Last Supper have gotten bigger as time passed – way bigger. This finding seems to obviously suggest that as time passes, we eat more and more, which should raise some concerns; overeating is one of the main causes of the growth of obesity cases (d’oh).

“We took the 52 most famous paintings of the Last Supper (from the book ‘Last Supper,’ 2000) and analyzed the size of the entrees, bread and plates, relative to the average size of the average head in the painting,” said Brian Wansink, the John S. Dyson Professor of Marketing and of Applied Economics and director of the Cornell Food and Brand Lab.


The analysis was aided by computers design software that enabled the researchers to scan, rotate, and calculate size of objects regardless of their orientation.

“The last thousand years have witnessed dramatic increases in the production, availability, safety, abundance and affordability of food,” said Cornell’s Wansink, author of “Mindless Eating: Why We Eat More Than We Think.” “We think that as art imitates life, these changes have been reflected in paintings of history’s most famous dinner.”

It’s been known for quite a while now, that especially in Western Europe and North America, people eat way more than they need. The thing is your body if you eat more than you need all the time, your body will be tricked into thinking it needs more than it actually does. You can also eat more because it takes about 15-20 minutes for your brain to process the fact that you don’t need any more food; so you could be even feeling hungry, and actually not need anymore. Anyway, I remember an old saying I heard from some elder people, that went something in the lines of: “The best meal is that which leaves you slightly wanting more”. Maybe there’s some truth to that after all.