Brain stimulation can reduce food cravings

Brain stimulation

It’s not entirely clear how DLPFC works to reduce food cravings, but evidence suggests possible effects on the “reward centre” of the brain and/or enhanced cognitive control over cravings.

Non-invasive stimulation of a specific brain area can reduce food cravings, particularly for high-calorie ‘appetitive’ foods, according to a review in the Psychosomatic Medicine: Journal of Biobehavioral Medicine, the official journal of the American Psychosomatic Society. However, there’s not yet consistent evidence to show that brain stimulation can reduce actual food consumption, according to the research review by Dr Peter A Hall and colleagues from the University of Waterloo, Ontario, Canada.

In their paper, ‘Effects of Noninvasive Brain Stimulation on Food Cravings and Consumption: A Meta-Analytic Review’, the researchers analysed previous studies evaluating the effects of non-invasive brain stimulation on food cravings and food consumption. Stimulation studies have targeted a brain area called the dorsolateral prefrontal cortex (DLPFC), which appears to play a role in the “conscious regulation of food craving and consumption of calorie-dense foods.”

The review identified eleven studies evaluating the effects of DLPFC stimulation on food cravings and/or consumption. The studies included human volunteers in laboratory settings, most often women who reported ‘strong and frequent’ cravings for high-calorie snack foods. All studies used an appropriate sham stimulation procedure.

Of eight studies providing data on food cravings, all but one showed a significant effect of brain stimulation. Meta-analysis of pooled data from these studies suggested a “moderate-sized effect” of DLPFC stimulation on food cravings, roughly half a point on a four-point self-rated scale.

Just one of the two types of stimulation studied had a significant effect on food cravings, a technique called repetitive transcranial magnetic stimulation (rTMS). The other technique evaluated, transcranial direct current stimulation, did not significantly affect cravings.

In contrast, the results of nine studies providing data on actual food consumption were inconsistent. The pooled data analysis suggested no significant effect of brain stimulation.

Another two studies evaluated the effects of treatment using repeated sessions of DLPFC stimulation. One study found a significant reduction in total food intake after daily stimulation, while the other did not. However, there was some evidence that stimulation specifically reduced consumption of carbohydrates.

That’s important, because calorie-dense snack foods are often implicated in the development of obesity. One reason it’s so difficult to lose weight by dieting is that the person has to overcome the “natural preferences” for these types of appetitive foods. It’s not entirely clear how DLPFC works to reduce food cravings, but evidence suggests possible effects on the “reward centre” of the brain and/or enhanced cognitive control over cravings.

The available data support the conclusion that DLPFC stimulation reduces food cravings, the authors believe. “These effects seem to be strongest for rTMS neuromodulation methods and are moderate in magnitude,” they write

While so far there’s “no reliable effect” of brain stimulation in reducing overall food consumption, studies do suggest a possible effect on intake of carbohydrates. Hall and colleagues make suggestions for future research, clarifying the potential benefits of repeated sessions of rTMS and focusing on actual food consumption, especially calorie-dense snack foods.

“Stimulation of the dlPFC modulates cravings for appetitive foods in single-session laboratory paradigms; when estimated separately, the effect size is only significant for rTMS protocols, they conclude. “Effects on consumption in laboratory contexts were not reliable across studies, but this may reflect methodological variability in delivery of stimulation and assessment of eating behaviour. Additional single- and multi-session studies assessing eating behaviour outcomes are needed.”