I had my left knee replaced four years ago. After many set­backs and four knee oper­a­tions, I am finally get­ting my life back on track. However, I have put on a lot of weight: now 23^st 10lb, I badly need some sort of dir­ec­tion. Can you help?

I am sure you under­stand very well that you need to lose weight for the sake of your knees. And that you will need to work hard on devel­op­ing and keep­ing strong leg and knee muscles for the rest of your life. As these two tasks make the dif­fer­ence between inde­pend­ence vs pain and dis­ab­il­ity, con­sider the effort it will undoubtedly take as a major invest­ment in your future hap­pi­ness.

Gather around you as much prac­tical sup­port as you can. Through your GP or privately, get your­self to a nutri­tion­ist to write you an eat­ing plan. Discuss weight-​loss med­ic­a­tion with the GP. For very over­weight people a com­bined approach of drugs, exer­cise and diet is usu­ally best. But the guidelines for being offered pills are strict, and many GPs will expect you to lose the first vital pounds through your own efforts. Be clear: the drugs will not work without life­style changes, too.

Also ask your GP to recom­mend you for a local “exer­cise on refer­ral” gym place, where you will be set up with a super­vised pro­gramme and prob­ably some group encour­age­ment. If this is not avail­able, seek out a friend who is really com­mit­ted to get­ting fit and join the gym together, with a pledge to help each other achieve your fit­ness goals.

Don’t just think “exer­cise”, but “activ­ity” and “fun”: a twice weekly gym visit fol­lowed by five days of being a couch potato is use­less. Take every small oppor­tun­ity to get up out of a chair, walk places, use energy every hour of every day. Find a hobby, pas­time or volun­teer work that will get you out of the house reg­u­larly and make you feel happy.

At first, I sug­gest you focus your gym efforts on the sta­tion­ary bike, walk­ing in deep water, and doing exer­cises set by a physio or advanced fit­ness instructor to strengthen your legs. In the water, you can push your­self hard without wor­ry­ing about harm­ing your knee. Consider buy­ing a “rebounder” (mini tram­po­line) for home use, and do “bouncy walk­ing” on it (not jump­ing!) for, eg, five minutes a couple of times every day.

When you get fit enough to add out­door walks to your régime, try Nordic walk­ing poles; these reduce the load on your knees very effect­ively, help­ing you to stride out and walk for longer.

Set monthly goals, not just for weight loss but other achieve­ments, too. This is a long-​term ven­ture in which there will be phases when pro­gress seems to stop com­pletely. This is nor­mal: don’t be temp­ted to give up. Keep a diary and pro­gress chart (take pho­tos) to remind your­self, when you lose heart, where you have come from, what you have over­come already and how much more you know you can achieve.