Sugary foods are not a good choice in the morning and instead of dairy milk use plant based milk for a healthier non-sweet cereal breakfast.
Homemade oatmeal with honey and dried fruit, sure. Store bought cereal products however, are loaded with processed sugars. Nothing will make you gain weight faster then eating sugar especially processed sugar products. Stick to honey, saccharine, and natural sugars found in fruit and many veg. Avoid table sugar, brown sugar, starch (potatoes are loaded), and processed sugar, i.e cereals and sugary treats.