DS1 (12) does lots of sport and walks 3 miles round trip to school each day. Eats like a horse but stays a healthy shape.
DD1 (10) is not keen on sport and walks ~1.5 miles round trip to school each day. She loves to play in her room or just read. She's gradually got overweight - since about 6 yrs. Not obese but a noticeable "beer" belly.
We eat healthily at home. Sweets maybe once a week. She snacks on apples and other fruit. I thought she was maybe she was getting too many extra calories at friends houses - lots of pizza, chips and ice cream (which she thinks is fab...) However we've just had a month away all together where I could see exactly what she was having every day (same as us). We all stayed same weight and she gained. I think she just needs less.
My dilemma is how to be "fair" with portion sizes at meal times. They are close in age and have always had the same. If DD eats same as DS she'll pile on weight. If she thinks she's getting less she feels hurt and hard done by. How can I solve this diplomatically please?