I've always had the physical ability to climb, but the big improvement this year is simply from losing weight. One kilogram of body weight over a 30-minute climb is one minute in time. That adds up to about 10 minutes over a three-week race, and if you start to add up the fact that you are shifting less weight every time you go up those little rolling hills we had on Thursday, every time you sprint out of a corner, it accumulates to a heck of a lot of time and energy.
I was climbing fairly well in the 2007 Tour, but I've lost seven kilos since then: 78 to 71. It's taken nine months, in little increments, without any sort of crash diet. I've had regular check‑ups with Nigel Mitchell, the nutritionist at the Olympic team, to make sure I'm only burning fat, not any muscle. The last one was the day before the national championship, 28 June. He said I didn't have an ounce of fat left on my body. I was at 4% body fat, which is just at the point where you begin to burn muscle because there's nothing else left. It's not a very healthy level to be at, but it's only for these four weeks. It's been perfectly timed. As soon as the Tour is finished, my wife Cath is going to tie me up and force‑feed me cake.
I'm also more efficient on the road because I have done no track work since Beijing. I used to be like a Formula One car, I could go very fast for a short time and when the petrol ran out that was it. Now I'm like a diesel, I can go all day. Rather than four minutes flat out, it's six-to-seven hours, riding at threshold for one or two hours in a mountain stage.