My sister-in-law has a severe eating disorder, which manifests itself as highly restrictive eating. She doesn’t recognize it as an eating disorder and claims she has “food sensitivities.” At first, she was just gluten-free, but she now avoids dairy, nuts, random unrelated meats, certain fruits, and some vegetables. She’s had allergy testing, but the doctors haven’t found anything. None of this generally upsets me, except I wonder what my obligations are over the holidays.

While it is certainly possible that the sister in law suffers from Orthorexia nervosa (an eating disorder that involves a fixation on healthy eating)

it is ALSO possible that SIL has genuine issues with foods

There are lots of genuine food issues that are not anaphylactic allergies

- multiple foods from different food groups can trigger migraines

- multiple foods from different food groups can trigger psoriasis flares

- multiple foods from different food groups can trigger mast cell flares

- foods that are high in FODMAPS can trigger digestive agony for people with irritable bowel syndrome

Given how many people we've seen in letters dismissing life threatening peanut allergies,

I think there's a 60% to 80% chance that SIL actually does have a genuine food issue, but that it's an food intolerance rather than a food allergy.

I think there's a good chance that SIL's food avoidance is not random and capricious, but that rather SIL is avoiding one or more of:

- FODMAP rich foods; or
- migraine trigger foods; or
- psoriasis trigger foods;
- or high salicylate foods;
- or high amine foods.