After Christmas, I feel ready to burst. I weigh myself. I weigh a full 100 kg – at a height of 1.80 m. Something must be done. But what exactly? I hate diets. Which is why I turned to 23&me, a Google subsidiary, by sending the laboratory-diagnostics company a sample of my saliva, carefully packaged in a plastic tube. (By the way: 33% of all search queries on the subject of “weight loss” are carried out by men.) The price, including express delivery: $150.