The variety of sugar substitutes on the market to satisfy the sweet tooth of the population while reducing calorie content can often be confusing. To add to the confusion, experts have found that “diet” varieties of foods and beverages may, in fact, increase appetite.
Artificial sweeteners are increasingly used as a substitute for sugar as they achieve the same level of sweetness in a product while contributing little to no calories.
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While these sweeteners are widely used in foods and beverages marketed as “sugar-free” or “diet,” a new study published in the journal Cell Metabolism reveals how artificial sweeteners affect the brain and the effect it has on regulating appetite and altering taste perceptions.
The study, co-led by the University of Sydney, discovered that there is an area of the brain that senses and integrates the sweetness and energy content of food.
When exposed to a diet laced with high quantities of the artificial sweetener, sucralose, the researchers found that animals consumed more food, which suggests that artificial sweeteners can make you feel hungrier and, as a result, eat significantly more. Sucralose is derived from sucrose and is up to 650 times sweeter than sugar.
“Through systematic investigation of this effect, we found that inside the brain’s reward centers, sweet sensation is integrated with energy content. When sweetness versus energy is out of balance for a period of time, the brain recalibrates and increases total calories consumed.”
Associate Prof. Greg Neely from the University of Sydney’s Faculty of Science
The team, from the University of Sydney’s Charles Perkins Centre and the Garvan Institute of Medical Research, chronically exposed fruit flies to a diet containing sucralose for more than 5 days.
When the fruit flies were subsequently given food that was naturally sweetened, the flies consumed 30 percent more calories.
“When we investigated why animals were eating more even though they had enough calories, we found that chronic consumption of this artificial sweetener actually increases the sweet intensity of real nutritive sugar, and this then increases the animal’s overall motivation to eat more food,” says Associate Prof. Neely.
The researchers identified that artificial sweeteners stimulate appetite by triggering a complex neuronal network that responds by alerting the diner that not enough energy has been consumed.
“Using this response to artificially sweetened diets, we were able to functionally map a new neuronal network that balances food’s palatability with energy content. The pathway we discovered is part of a conserved starvation response that actually makes nutritious food taste better when you are starving,” adds Associate Prof. Neely.
In addition to identifying increased appetite in fruit flies, Prof. Herbert Herzog’s lab at the Garvan Institute of Medical Research tested the theory in mice to see if mammals would have the same response as fruit flies.
Similarly, when exposed to a high sucralose-sweetened diet for 7 days, the mice increased food consumption, and the same neuronal pathway was activated.
“These findings further reinforce the idea that ‘sugar-free’ varieties of processed food and drink may not be as inert as we anticipated. Artificial sweeteners can actually change how animals perceive the sweetness of their food, with a discrepancy between sweetness and energy levels prompting an increase in caloric consumption,” Prof. Herzog concludes.
Also revealed in the study was that hyperactivity, decreased sleep quality and insomnia was elevated with consumption of artificial sweeteners. These behaviors are often displayed in those fasting or in a mild state of starvation and have been linked with artificial sweeteners in other human studies.
With artificial sweeteners recommended as an aid to control weight without substantial evidence on how they impact the brain or regulate hunger, the new findings highlight that artificial sweeteners may add to the risk of obesity rather than assisting in reducing the risk through weight control.