Friday, 7.30pm, Bio According to this documentary series, 13 million adults in Britain are overweight, as many men as women. ‘‘ We eat too much and we exercise too little,’’ says the narrator, as if she weren’t stating the bleeding obvious. Then it’s down to case histories. In this second episode we meet two men, one who has been battling the bulge for most of his life, and another who, as Paul McCartney sang in Yesterday, is just half the man he used to be. Gruesome at times, especially during surgical procedures, but it sure gets its worthy message home.