Psychology Today

This article is long. Read the whole piece in the link, I'll post the section that I find true, and really annoying :

However, music may also have a negative effect on mood, and in some situations influence whether or not people make healthy food choices. The type of music is unimportant; rather, it is the volume. As the loudness of music increases, it can have a direct effect on heart rate and arousal, according to the above-cited review in Advances in Consumer Research. Very loud music causes heart rate and general arousal levels to increase, and those hearing the music often become more excited than when listening to quieter music.

Restaurants often increase the volume of the music to such a high level that diners must shout at each other in order to be heard. Recently while walking my dog, I passed by a restaurant whose noise level was so high that code compliance officers were called to make the restaurant reduce the volume. A server was standing outside a few minutes before the restaurant opened, and I asked him why the noise level was so high. “The restaurant owner does it deliberately. It gets the diners excited, there is a ‘buzz’ and people may order more food or more expensive wine,“ he told me. When I asked him how the diners could talk with such loud noise, he laughed and said, “Maybe they text each other instead.”

The effect of loud music on the eating habits of diners has not gone unnoticed. Producing a high state of arousal, or even stress, in diners is thought to weaken or remove their self-control over eating and drinking. Loud music may produce such an unpleasant sense of arousal in diners that they find themselves choosing high-fat and/or high-sugar 'comfort' foods in order to diminish their stress, according to the Biswas review. Conversely, eating in a relaxed environment with low levels of ambient music might have the opposite effect. Diners, relaxed and with increased self-control, may make wiser, healthier food choices, and perhaps consume less food.