Tag archive for food

Fatty Foods Affect Brain Before Weight

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High amounts of fat in food, such as ice cream, not only affect a person’s stomach but also their brain. Some of the fat travels to the brain, which then causes the brain to send out signals to all of the cells in the body. These signals “tell” the cells to disregard the hormones leptin and insulin, which tell the body to “stop” eating to regulate body weight. When a human eats, these hormones send signals to the body to stop eating once the body is full, but these hormones do not always work when a human eats something enjoyable like “junk” food. Leptin is released to stop the feeling of hunger by fat tissue in the body and insulin slows the desire for food by increasing in the pancreas after detection of blood sugar from a meal.

In a study done at the University of Texas Southwestern Medical Center at Dallas, Dr. Deborah Clegg analyzed what kinds of fats affected the brain in this way. Dr. Clegg believes that the fat actually changed the chemical composition of the brain because the fat is incorporated into the brain. Dr. Clegg performed this study by looking at effects of different fats on the brain of animals after exposure by three different methods: injection directly into the brain, feeding the animal through a stomach tube, and infusion into the carotid artery a few times a day. Palmitic acid and oleic acid were the specific fats used. Palmitic acid is a saturated fatty acid and is found in foods such as butter and beef while oleic acid is an unsaturated fatty acid found in food such as olive oil. The results showed that palmitic acid affected the signaling pathways of the leptin and insulin over about three days while the oleic acid did not affect the hormones. These studies were done on animals but Dr. Clegg believes that the saturated fatty acids will affect a human’s brain in a similar way. In another study with rats, the saturated fats, especially palmitic acid, caused the insulin modulator to localize to the cell membranes in the hypothalamus, which slowed the insulin signaling in the brain. Dr. Clegg hopes to soon determine a way to reverse the effects of the palmitic acid on the brain signaling.

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Chocoholics Beware: Addiction could be worse than you think…

A recent study by the Scripps Research Institute Committee on the Neurobiology of Addictive Disorders reveals an interesting fact about food addiction. While it has been known that sugary or fatty foods can cause an addiction much like that of heroin or alcohol, Pietro Cottone and his team proves that the “sugar high” isn’t the only reason for the addiction. In fact, in his studies with rats, he found that there is also a negative reinforcement system, much like that found in drug addicts, which can cause feelings of anxiety during a withdrawal of the sugary or fatty foods. This increases the probability for continued addiction. Hypophagia, or under-eating of regular (non-preferred) foods, is common when rats and people are influenced by food addiction. Cottone’s hypothesis involved a non-nutritional explanation for this phenomenon, which is commonly credited to an “energy compensation” theory. The nutritional explanation of hypophagia is that it stems from a “corrective energy homeostasis mechanism which opposes weight gain.”Chocolate.jpg

The study to test this hypothesis was conducted with male Wistar rats that were fed a chow diet (A/I) which was preferred to their regular Chow, and were also offered the choice of a chocolate-flavored chow. The rats were given the regular Chow for 5 days, and then were given the highly preferred sugary chow for 2 days. While they ate roughly the same amount of regular food each day, the rats over-ate the sugary chow, and then under-ate the less-preferable but equally acceptable chow (hypophagia). The group used A/I as well as the sugary chow, which had the same initial levels of energy intake and weight gain, to prove that the rats’ addiction was more than just nutritional. Given their similar caloric value, the rats still preferred and overate the chocolate diet more than the preferred A/I chow.

Ultimately, the group discovered that the rats going through chocolate withdrawal spent more time in corners of a maze, rather than the open parts, illustrating the previously mentioned anxiety effect. They found the anxiety to be attributed to corticotropin-releasing factor (CRF), which is involved in stress-response in the brain (commonly found in drug and alcohol withdrawal cases). This research marks the first time this factor was indicated in a type of food, or chocolate addiction. Could a CRF blocker be the answer to every chocoholic’s addiction? Cottone says yes.

What I found most remarkable about this study was the severity of chocolate or food addiction, and how it could be equated biologically to alcohol or drug addiction. This study suggests that on-and-off dieting could increase addiction and anxiety in withdrawal of that addiction.

PNAS, 2009. DOI: 10.1073/pnas.0908789106

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