The summer holidays are upon us, and with them the annual dash to lose a few pounds to feel better in our swimsuits and shorts. But the days of the crash diet are over; increasingly, we’re demanding ways to lose weight realistically and sustainably.

Experts agree that the sunshine is a great motivator to make some easy changes. Here they offer their advice for slimming down and feeling better for the summer and beyond.

1. Eat nothing between 8pm and 8am

Intermittent fasting – when you give your body extended periods without food to kickstart the process of ketosis, where fat is broken down and used for energy, rather than carbs – has become hugely popular. Dr Michael Mosley, who helped devise the method with his book The Fast Diet, suggests you ease your way in. "How you start intermittent fasting very much depends on you and your sort of personality type," he says. "I normally recommend people start gradually. So, start by consuming your food in a 12-hour window, and fasting the rest of the time. Once you’ve got used to that, move on to a 10-hour period of eating."

Mounting evidence shows it is better if you finish your evening meal earlier, rather than having a late meal, skipping breakfast, and then fasting until lunchtime. "I recommend you try and stop eating by 8pm and then not eat anything again with calories before breakfast the next day. If you are fasting for 12 hours, you can have breakfast at 8am."

Later, suggests Dr Mosley, you might try moving the start time on a little bit to 10am for breakfast. "In that case, you might want to have something like a meal replacement shake for breakfast, which might be more convenient if you’re at work. If you are really pushing it towards eating all your food in eight hours, then you’d probably aim for something like skipping breakfast altogether and having lunch around noon or 1pm." But important: consult your doctor before making any changes to your diet.

2. Crack on at breakfast

Start the day with eggs, says Dr Mosley: "Boiled, poached, scrambled or as an omelette – they’ll keep you feeling fuller for longer compared to cereal or toast. Delicious with greens and parmesan or smoked salmon."

Eating plenty of protein is an important part of the Mediterranean diet – a way of eating that is high in vegetables, fruits, legumes, nuts, beans, cereals, grains, fish, and unsaturated fats such as olive oil. It usually includes a low intake of meat and dairy foods. Many experts says that the Mediterranean diet has been linked with good health, including a healthier heart.

Dr Mosley agrees: "A low carb Mediterranean diet has unique power not just to restore your body’s ability to reach its ideal weight and stay there, but also to cut your risk of serious disease. It doesn’t come from a place of restriction but rather it’s about eating more of the right foods. Not only will these foods keep you feeling full, but they also offer important nutrients and health benefits, and taste delicious."

3. Improve your liquidity

Registered UK dietician Sian Porter says summer is the perfect time to go for foods with a high-water content, as they will refresh you as well as fill you up. "High water foods have a low energy density," says Porter. "That means they have fewer calories per ounce of food." Think fresh fruits and veg rather than biscuits. Fish and lean chicken are also low-density foods.

Studies have shown people tend to consume about the same amount (weight) of food each day, but not necessarily the same amount of energy (or calories). So it may be possible to consume less energy, without feeling hungrier, by eating a lower energy density diet.

4. Breathe harder

While exercise alone will not help you lose the stubborn fat from around your middle, says Dr Mosley, it can be crucial for helping reduce the risk of regaining fat as well as lowering blood sugar levels and improving insulin sensitivity.

Dr Mosley is a fan of HIIT (high-intensity interval training – short bursts of strenuous exercise) and his exercise bike. "Not only is it a highly effective way to get fit," he says, "it’s also unbelievably quick. I recommend just 10 minutes on a static bike three times a week, plus quick strengthening exercises which don’t require special equipment. If you don’t have an exercise bike you can try pedalling on your road bike furiously up a hill, running up the stairs, or doing short sprints when out on a run, or just pick up your walking pace until you are breathing hard. The main thing is that these bursts should be brief (30 seconds maximum when it comes to the stairs, or running), but hard enough to get your heart rate up." Again, consult your doctor before going on any exercise regimen.

5. Soup it up

Start a meal with a bowl of cold soup like gazpacho, suggests Porter. Not only will it add more fluid to your day, but studies at Penn State University in 2007 showed that drinking a low-calorie soup before a meal can help reduce the amount of food you eat.

6. Get an extra hour’s sleep

Nutritionists believe that not getting enough sleep alters our metabolism so our bodies cannot process food as effectively, says Dr Mosley. "An extra hour’s sleep could help you to lose weight within weeks." A study from the American Institute for Cancer Research claims late nights mean we snack more, and exercise less.

"Getting enough sleep when trying to lose weight," adds Dr Mosley, "means your body will reset its hormones to make better food choices. With a high-fresh, low-carb diet, intermittent fasting, and regular exercise, you can completely reset your appetite. You won’t want to eat unhealthy food, and the weight that you lose won’t come back."

For better rest, reduce the intensity of artificial light in your home by using dimmer switches or low wattage bulbs, switch off technology and avoid drinking too many liquids before you sleep.

7. Choose whole grains

Eating three portions of whole grains a day slows the onset of middle-age spread by half, a study at Tufts University in the US has found. People who ate the fewest whole grains (the entire kernel, including the bran and germ) saw their waist size swell by around 1.2in every four years. However, for people who regularly ate three portions of whole grains a day this figure dropped to around 0.5in. The most common whole-grain foods in the study were brown breads and porridge oats. Whole grain is healthier than processed grains because the outer layer is packed with fibre and the inside is rich in B vitamins, antioxidants and healthy fats.

Dr Caleigh Sawicki, of Tufts, says: "The presence of dietary fibre in whole grains can have a satiating effect, and the magnesium, potassium, and antioxidants may contribute to lowering blood pressure. The soluble fibre may have a beneficial effect on post-meal blood sugar spikes."

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