Generally, personal expenses are not allowed as business expenses. Business expenses are those expenses that are ordinary and necessary for that type of business.
If she was running a food truck, for example, and purchased raw materials with a business credit card, and diverted some of the ingredients to her home kitchen for personal use, that is absolutely not allowed as a business expense (that's embezzlement, even from yourself). However, if she ate her own meals "on the job" (in between customers) that would probably be allowed under a couple of different theories.
I'm unclear on the situation here. I think I hear you saying that she purchases pre-packaged weight loss meals, and sells them to others, and also consumes the meals personally. I can't see how the meals she personally consumes are deductible business expenses. The owner of a business can sometimes deduct meals, for example, if they entertain a potential client with the goal of expanding the business and recruiting new customers and clients, that shared meal is sometimes allowable. But I don't see how that applies here.
