Health Secretary Alan Johnson has warned that obesity may prove to be as big a crisis as climate change (see http://uk.news.yahoo.com/rtrs/20071014/tuk-uk-britain-obesity-fa6b408_2.html). I'm not entirely convinced by his line of reasoning, but I'm sure that obesity could make climate change worse. If we have more obese people, we won't be able to fit the same numbers of passengers in planes and this may lead to more flights and greater CO2 emissions. Also, there will more food in fridges, necessitating increased use of electricity.
On the other hand, if people find it difficult to squeeze into cars, we may find that our roads are less congested. So perhaps obesity is good for the environment? It's all so confusing.