Sherlock glanced at the array of food he was about to scan.
"Digestive problems," he said flatly.
"I'm sorry?" She was a relatively towering two meters even, with contacts obscuring the blue of her eyes and, on top of the digestive problems, a minor thyroid condition that forced her to wax a dark mustache every week or so. Suspicious, but not the man Sherlock was hunting.
"Prunes would be too obvious, so you bought dried papaya," he explained, weighing the little bag and dumping it into one of her reusable plastic sacks. "Don't tell me you like the texture- I saw you contemplating the Swedish fish as an impulse purchase, but you decided on a much more palatable chocolate bar. Commendable."
"I... like the taste," the woman said weakly.
"Papaya is in season and we have it in our fresh fruits and vegetables area," recited Sherlock. "As a member of the frequent shoppers club and a regular buyer of fresh pomegranate, there is no way you wouldn't know, if you actually liked the taste. Additionally, this herbal supplement has been demonstrated to be useless except in loosening stool and increasing the risk of colon cancer. Finally, you have purchased the low-fat versions of all your preferred packaged products that offer it – despite being of optimal weight for your height and build – and exactly one can of each type of bean that we stock, the surest sign that you intend to change your diet and don't yet know what you like that is healthful. I recommend the navy beans for fastest relief."
She spluttered, reddened, paid, and left. Sherlock turned to the next customer.
"Just work out if it's that important. Your body won't grow muscle if you don't force it to."
This customer was about thirty centimeters shorter than his predecessor, prematurely balding and rail-thin from a combination of stress and self-imposed starvation only barely on the near side of anorexia. "What?" he said, not feigning ignorance but still confused.
"Soy. Soy, soy soy." Sherlock indicated and scanned a different soy product with each repetition of the word. "Soy, and... yes, more soy. Vegan too, I gather. Energy drink – you are aware that correlation isn't causation, right? Athletes don't look like that because they drink this trash. Lean salmon – not vegan, pescatarian, it's always something – and a pound of almonds. Eat some carbohydrates, why don't you?"
He stalked off without a word. Sherlock glanced at the final customer of the day.
"Herpes."
"How could you possibly know that?" exploded the man, who additionally displayed symptoms of alcohol overuse and a deeply troubled marriage.
Sherlock pointed wordlessly at the herpes medication from the pharmacy department.
"Oh."