What do you mean? - The pump being too heavy? No problem. Children use insulin pumps and cope with the weight. - Pumps not suitable for someone who is heavier? Not an issue for me but the only problem I can see there is about insulin dose. Typically, a pump holds 200 units of insulin which is used for basal and bolus and should last 3 days. Heavier people, often, need more insulin but 200 units over 3 days is enough for most people. I think there are some pumps with 300 unit cartridges. - Pumps making you put on weight? The only thing I have read/heard about this is that it is easier to snack because it is easier to dose when you only have to press a few buttons compared to getting your pen out, putting a needle on it, calculating the dose, dialling up the dose and injecting.