How to avoid fatty or unhealthy foods? Just smell them for two minutes

An interesting discovery was made by a research team from the University of South Florida. The study, published in the Journal of Marketing Research, 

describes how a particular tactic, which can take only a couple of minutes of time, can prove very useful in avoiding eating unhealthy foods or consuming high-calorie meals.

According to the study, if you are faced with fatty foods or a portion of fried food, for example, to avoid consuming them or in any case to eat less, just smell them for more than two minutes. It is known that sniffing a good snack (and usually "good" means not really healthy) can entice people because it whets the appetite.

However, prolonging this olfactory phase, according to the study, the opposite effect occurs. Sniffing, therefore, becomes a deterrent because the exposure to the aromas, which initially can captivate and entice you to eat, begins to trigger a reward in the brain leaving the person satisfied as if he had tasted food.

Dipayan Biswas, the lead author of the study, also specifies it: "Subtle sensory stimuli such as perfumes can be more effective in influencing the food choices of children and adults than restrictive policies".

The direct connection between the duration of the exposure time to perfumes and the desire to eat was discovered by the researchers after a series of tests during which they used a nebulizer that could give off scents of healthy food (strawberries and apples) or fatty foods or not too beneficial (stuffed biscuits or pizza).

Participants exposed to the smell of "unhealthy" foods for 30 seconds were more likely to want to eat them. When instead they were exposed to the same smell for more than two minutes, they no longer found those desirable foods and chose apples or strawberries.

• Scientists decode how mouse brains distinguish one smell from another

Researchers trained mice to recognize certain odors to artificially create (credit: DOI: 10.1126 / science.aba2357 | Science )

How the mammalian brain "smells" and distinguishes them from thousands of other different smells has been further understood and decoded by a team of researchers from the NYU Grossman School of Medicine and NYU Langone Health, as a press release notes appeared on the Langone website.

The uniqueness of the smells comes from the time and order of activation of the glomeruli, cells that line the nose, and that send electrical signals to the olfactory bulb and brain neurons.

Through a technique known as optogenetics, the researchers intercepted, for the first time, an electrical signature perceived as a smell in the center of the smell, the so-called olfactory bulb, of mice. This electrical signal can be transmitted to the brain even when the smell is not literally perceived through the nose.

The researchers, in fact, starting from an artificially created simulated odor signal, then manipulated this odorous signal which then became a nervous signal so that the brain cells were activated by illuminating them with a beam of light.

They then trained the mice to recognize a particular signal generated by the activation of the light of six glomeruli giving them a reward in water only when they perceived the correct smell and pushed the lever.

By changing the times the mix of activated glomeruli, an effect was obtained on the level of perception of the mice of the smell and therefore on the accuracy with which they acted to obtain the reward.

"Our results identify for the first time code for how the brain converts sensory information into the perception of something, in this case, a smell," explains Dmitry Reinberg, neurobiologist and senior author of the study. 

Unlike other senses, such as sight and hearing, that of smell still has several dark sides as regards the discernment that we do from one smell to another.

"In facial recognition, for example, the brain is able to recognize people based on visual cues, such as the eyes, even without seeing someone's nose and ears," explains Edmund Chong, one of the researchers who performed the study published in Science. 

• The unhealthy diet also affects the brain and not just the physical aspect

An unhealthy diet rich in fatty foods and carbohydrates can affect not only the physical appearance, substantially bringing greater fat, but also the brain according to a new study conducted by researchers at the University of Yale.

Specifically, the researchers found that unhealthy diets can contribute to irregularities in the hypothalamus, a region of the brain that also controls body weight-related metabolism.

With this study, researchers confirm that hypothalamic inflammation occurs as early as three days after consuming high-fat foods, so before the signs of obesity can manifest.

These are very fast changes, possibly not directly caused by body weight, to which a particular cellular mechanism must be connected which the researchers themselves, led by Sabrina Diano, professor of cellular and molecular physiology and of neuroscience and comparative medicine, wanted to discover.

They, therefore, analyzed animals exposed to a high-fat diet, in particular observing inflammation in the hypothalamus.

They discovered structural changes in microglia cells, those cells that usually regulate inflammation of the central nervous system.

The same structural changes in microglia were in turn caused by changes in the mitochondria that were smaller.

In turn, this change in mitochondria was caused by the intervention of a protein, called mitochondrial decoupling protein 2 (Uncoupling Protein 2 or UCP2), a protein that regulates the supply and use of energy in mitochondria.