Military marathoner continuing to gain weight

Question
This question is about my 32 year old husband. I write because we are at our wits end. Despite a low-calorie diet and exercise (in the last year and a half he has run both a half and full marathon and a triathlon) he continues to slowly gain weight.
At 6' 1" and 210 lbs he is the smallest person in his immediate family. His brother, mother and sister are all taller and outweigh him by at least 40 lbs. He understands that his genetics are working against him, but is fighting as hard as he can to maintain a healthy weight.
Chris is a sergeant in the MN National Guard and barely squeaks by the height-weight requirements. This is a consistent sore spot especially when he can run circles around his troops who weigh half as much as him.
He works out (cardio and weights) at least 4 times a week and eats a low calorie diet: lots of fresh veggies and fruits and protein comes from lean turkey, egg whites or tins of tuna. He drinks gallons of water and rarely touches soda or other sugary drinks.   We estimate that his caloric intake is around 1200 calories/day.
He抯 seen nutritionists, physical therapists and fitness coaches. Most insist that he needs to up his calories: but as soon as he does he sees an immediate jump in weight.   Others say he needs to up his activity: which is hard to do being a full-time student with two part-time jobs, a house, a family and military career.
At my insistence he has had blood work done:  his cholesterol is fine, his thyroid seems to be fine and nothing in any of the other tests has come back with answers.  
Symptoms that I think may be significant: he has constant headaches and joint pain, he is always tired,  but has bouts of insomnia, has trouble focusing on routine tasks, and is on medication for high blood pressure.
My husband is always hungry and he rarely gives in.  (He lives for his treat once a month or so: Chicken wings and beer with the guys.)  I worry for the day that he does give up.  Not because I won抰 love him at any weight but because of the loss of our active lifestyle.
Is there anything else we should be looking at/for?  His goal is ultimately to lose weight, but at this point we would both be happy to just stop the weight gain.

Answer
Krista,

I feel for you both--and I can certainly see why you are at your wits end.
The best advice I can give you is to find an expert locally to see for several visits in person. Most hospitals have out-patient dietitians, and your husband may be able to get an appointment through military healthcare. My guess is that he is really eating a lot more than 1200 calories. He might also be able to have a test done to see what his resting energy expenditure is just for more information to know what you're up against. I would love to hear what you find out.

Good Luck!

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