I would suggest that you supplement your daily diet by drinking some watered down (to lower the osmolality level) Peptamen 1.5 drinks.
During a flare - you could even cut out all food, and just drink these. Each carton is 375 calories x 9 / day = 3,375 calories. So even if you just supplement your diet with a few of these drinks, you could increase your caloric intake significantly. For your 500 calorie shortfall, you could get by with drinking just 2 a day.
You can buy them directly from Nestle, and they will deliver to your door. But, they are rather expensive so check with your insurance carrier. Most of them cover the cost if the drinks are your sole source of nutrition. Just ask your doctor to write a prescription and send it in to a home delivery company like Apria Healthcare.
Hope this helps.
http://www.tchomemedical.com/IBS/SimpleCat/Product/asp/hierarchy/0E04/product-id/36716977.html
Peptamen 1.5
Peptamen 1.5 complete high calorie elemental nutrition is a ready to use elemental diet for elevated caloric requirements in patients with impaired GI function.
375 calories per 8.45 oz.
18% Protein (from enymatically hydrolyzed whey protein); 49% Carbohydrates; 33% Fat.
Caloric Density: 1.5 cal/mL
Nonprotein Calorie: Nitrogen Ratio: 116:1
MCT:LCT Ratio: 70:30
n6:n3 Ratio: 7.4:1
Osmolality:
Unflavored: 550 mOsm/kg water
Vanilla: 550 m/OSm/kg water
Free Water: 77%
Appropriate for lactose free (not for patients with galactosemia), gluten free, low residue diets.
Peptamen contains ingredients milk protein and is not appropriate for individuals with cow's milk protein allergy.
High caloric density to address nutritional needs in smaller volume.
Available in unflavored and vanilla flavor.
Sold in cases of 24 - 8.45 oz. cartons.