Get a bottom like Kylie's

Call it the Kylie effect, but it seems more of us want a work out that shapes our behinds. There's little doubt that we use our bottoms to seduce, which is why, when we pull out that sexy little black dress from the back of the wardrobe every year, we want to make sure we look as good making an exit as we do making an entrance.

But with only four per cent of women reported to be happy with the size of their bums, too many of us are sitting on it instead of moving it. Today, bottoms are broader and saggier than ever - the average size has swelled from a 12 to a 16 in 50 years - so it may take a little dedication to get your rear in gear.

"A major cause of the bottom sliding southwards is a sedentary lifestyle," says Kacy Duke, creative consultant for Equinox Fitness Clubs in New York and A-list trainer to stars such as Iman, Julianne Moore and Denzel Washington. "If you sit at a desk all day, then crash on the sofa all evening, your bottom will spread fast."

Buttocks store excess fat, so toning them can be tougher than for other parts of the body. If you're serious about improving a droopy derriere, cut your intake of refined foods and choose fish and chicken over other meats, as they contain fewer of the toxins that our bodies find difficult to eliminate.

"The best way to burn fat off the hips and bottom is to work the body aerobically and throw in targeted exercises that increase muscle use and reduce fat," says Duke. "Also, try daily brisk walking, hill walking, cycling or dancing all to an out-of-breath level."

Here are a few exercises devised by Duke. "They tone up the lower bodies of my clients and are guaranteed to get great results in weeks. Add these four moves to your routine at least two to three times a week to see a profound uplift."

The weighted squat

Holding a five-to-12-pound weight in each hand, stand upright with feet parallel and shoulder-width apart. Keep abdominals and buttocks tense. Lower yourself into a sitting position, as you would on a chair, hold for one second. As you rise, squeeze the buttocks. Repeat 12 times. Do three sets of 12, resting between.

The Duke curtsy

Stand upright with abs tight and hands on waist, heels and toes turned out slightly. In a single, fluid movement, bring your right leg back and towards the left side, bending both knees into a curtsy whilst keeping your back straight. Return to starting position and repeat 12 times before changing to your left leg. If necessary hold on lightly to the edge of a chair for support - but not for ever if you want the best results.

The gluteal leg lift

Start on all fours, with elbows and forearms resting on the floor. Keeping the foot flexed, the knee bent and the buttocks tense, lift your leg without arching your back. Keep your head up and your abs contracted. Bring your leg down until your knee touches the floor. Repeat 12 to 24 times on both sides. For added challenge, hold your leg up and "pulse" 12 times.

Under-the-bottom side lunge

Stand upright with your legs as comfortably wide as possible and toes turned out. With both hands hold one eight-to-15-pound weight, lunge to your right side and place the weight down on the floor close to the tip of your foot. Release the weight for one second, pick it up and return to the starting position, squeezing your buttocks as you come up and back to the centre. Repeat on your left side. Do three sets of 12 repeats.