My husband takes a salad to lunch daily usually consisting of cheese cherry tomatoes, cucumber, hard boiled eggs, mayo and a pickled onion. He is a manual worker so expends a lot of energy at work. He usually has a small tub of nuts or an apple as well as a chocolate biscuit obviously the biscuit is not suitable for you. He is not diabetic but follows the LCHF Diet to keep me company. (He has lost 15lbs I've lost 11!) if it is very cold he can take a flask of homemade soup.