In recent years a much talked about victim fad has been that of "food intolerance." It's a new malady that people can possess that explains why they have problems.
A whole industry of food testing sprung up with some highly dubious methods, using everything from kinesiology (nonsense involving supposed muscle testing), through to blood testing and hair testing.
The results are tiringly predictable, they will tell you that you should avoid wheat and dairy, and will often throw in something you'd never eat anyway ("Himalayan sea cabbage") just to look like they are being thorough.
Of course there are genuine medical reasons for some people not to eat these things, but they are rare and readily diagnosable by your GP. Chances are though, you don't suffer coeliac disease, you suffer from that worst disease of all - you want there to be an easy explanation for why you are overweight that doesn't involve the fact that you eat too much of the wrong stuff and don't take enough exercise.
Coeliac disease can be easily tested through a pin-prick blood test as there are blood markers for this genuine and unpleasant condition. But a food intolerance to Harrow Mind Cheese cannot be tested for in these ways.
The kinesiologists are the most ignorant of the bunch. They may get you to put some of the suspect foods in your mouth and test how strong your arm is. Any weakness must be a sign of an allergy, right? Some dispense with the food altogether than merely write the name of it on a piece of paper and get you to hold in in your hand. It's total hokum, yet people will believe these methods as being an accurate diagnosis and explanation.
You might be better off simply trying witchcraft for all the good it will do you.