what gives? wrote: I don't understand how they can train for marathons and still have a gut if there not out getting ripped drinking several times a week?
it isn't immediately clear how you would know the weight of some random jogger you saw in the street nor is it obvious how you would know what their weight was last month, so unless random joggers habitually turn up at your house to weigh themselves on your bathroom scales the basic premise behind your question, that they are not losing weight, exists entirely in your imagination, which probably explains why you find it so confusing.
also, unless these random joggers shouted out their Strava handles as they went by it isn't clear how you are able to properly assess the volume and intensity of their training and I would be particularly interested to know how exactly, from among the many hundreds of different reasons for going for a run, you determined that they are training for a marathon.
however, for the LRC lols, let's take the least likely assumption, that you have actually got a clue, and that these dudes are overweight, that they are training for marathons, and yet they are not losing weight.
the fuel you burn is determined by the speed at which you run. the precise point at which we change over from predominantly fat-burning to proportionally more carb-burning differs from person to person but generally, on average, running slow burns mostly fat and faster running burns more carbs.
these guys are probably not running fast enough to burn a lot of carbs. they are in fat-burning mode and their running is fuelled mostly by their middle-age paunch.
which means that the fuel they eat is not being burned, and it is therefore being turned in to fat to be stored around the body for later use.
therefore, their running is merely turning over their fat reserves. in one side and out the other. if they ran one faster session per fortnight they would probably start to lose weight.
yours, mr obvious.