It's a misconception that full-fat dairy products are 'bad' for you. Organic, full fat milk for example has not been mechanically altered to remove the cream and fat (naturally high in protein), and has not been subject to UHT (ultra heat treatment). It is thus a natural, non-fattening milk that can and should be consumed without worry.
Full fat milk only has a small percentage of fat in it anyway. It will not harm the body, and when used in moderation will not cause serious weight-gain or damage to your body. In fact, 'full fat' fermented foods are generally better for you because they are higher in protein, and lower in sugar than most 'low fat' (high sugar) alternatives.
Greek yoghurt for example has the most high-fat content out of all natural yoghurt, but it is enjoyed by many health experts because it is naturally high in protein because of the natural 'good' fat. Greek yoghurt, because of the way it is strained, can be also be tolerated by those who are lactose intolerant because it has a lower lactose content compared to plain yoghurt.
Compared to other 'low fat' options on the market Greek yoghurt is naturally low in fat, high in protein and overall a better, naturally fermented food. It has not been tampered with to make it 'low-fat' and is one of the healthiest snacks on the market. Much better than a 'low fat' snack bar anyway.