The images taunt us from women's mags, TV, the movies: svelte Hollywood celebs posing in impossibly tight dresses, not a bra-strap bulge, muffin or paunch in sight. How do they do it? Is it the cabbage-soup diet, lemon detox, high protein, low carb or simply not eating?
Less than eight weeks after giving birth, Victoria Beckham squeezed back into a pair of size-zero skinny pants and tottered off on skyscraper heels to shop in Los Angeles.
If Victoria has a secret, she's not telling. Neither are Nicole Richie or Katie Holmes, nor any of the other celebs who appear to pop back to size zero days after giving birth. In Hollywood, surplus fat is about as welcome as a cockroach in a cupcake.
In the real world, plenty of mortals struggle with weight gain and everyone has their pet weight-loss method, from forking out for pricey gym memberships or signing up with a diet company to swilling down litres of water, swapping butter for olive oil or eating a big bowl of cereal for breakfast instead of eggs.
But Auckland nutritionist MaryRose Spence, the author of Size Does Matter, says many people's weight-loss efforts are derailed by common myths. People keep hearing the same old messages about weight loss and, in some cases, they are the wrong messages.
"People think food for general healthy eating is the same as food for weight loss, and it's not."
With more than 65 per cent of New Zealanders overweight or obese, the messages need to change, she says.
People trying to lose weight may be doing themselves a disservice by starting the day with breakfast cereal. Because cereal is a carbohydrate, it does not give lasting energy, Spence says, prompting snacking later, particularly for people with a high muscle mass who process carbohydrates quickly. Toasted muesli is high in sugar and oils and loaded with kilojoules.
Most cereals are promoted in a way that makes people think they are the perfect food, she says.
"They can be high in fibre and low in fat, but do they keep you feeling full for long enough?"
Spence recommends adding protein, such as baked beans or eggs, to the first meal of the day. "You will get much better appetite satisfaction if you include protein."
And everyone should eat breakfast. "If you wake up and you are not hungry, you have eaten too much from 4pm the day before."
Most people should drink 1.5 litres of water a day minimum during summer and a litre during winter, Spence says. "But over-drinking won't do you any good. It just results in additional trips to the toilet, and possibly a loss of water-soluble vitamins."
AUT University Professor Elaine Rush agrees there is evidence of people drinking too much water. "Advertising does work. There are all the myths that go with bottled water." Rush says people can gauge whether they're drinking enough fluid by the colour of their urine.
Carbohydrates and protein
Restricting carbohydrates in meals is not sustainable, Spence says. "There are people who never have potato at night but you find the meat portion just gets a bit bigger, and that actually contains more calories."
Anyone who drops carbohydrates from two meals a day will notice they are tired by the end of a week on the diet, she says. "It doesn't meet enough needs nutritionally."
While eating more protein is good, Spence says recent studies show a small increase in the amount of protein noticeably reduces the number of calories eaten overall, but too much protein quickly leads to weight gain.
A good rule is to eat half a plate of vegetables, a quarter of carbohydrates and a quarter of protein, says Rush. Protein shakes and meal replacements also get the thumbs down. "There's a strong relationship between chewing your food and increased appetite satisfaction," Spence says.
Rush says eating plans should be about quality of life. "It doesn't matter how good the quality of the petrol you put in the tank is, it's getting it away from the kerb that matters. You need to be able to function."
Slogging away for hours at the gym is unlikely to make a lot of difference to weight-loss efforts, Spence says.
"You can do a lot of exercise, but unless you get the food right, nothing will happen." Once people are carrying extra body fat, exercise is not as effective as many think. Ideally, people should go for a brisk walk for 30 minutes a day.
"Any longer than 35 minutes a day may just make you hungry."
Dr Geraldine Poynter, who refers clients to Spence, says people find the idea of a half-hour walk more palatable. "A short, brisk walk is so achievable."
In terms of weight loss, it doesn't matter if they are "good" or "bad" fats - it's all bad if you eat too much.
Says Spence: "When you look at fresh salmon, seeds, avocado, overweight people think this is good for them but they are loaded with calories." Poynter says the information she learned from Spence was a surprise.
"I thought we were meant to have a lot of Omega-3, so I was eating salmon. She says it is better to eat canned salmon because it is not so fatty. At medical school we got so little nutrition information."
The glycaemic index has been a buzzword in weight loss in recent years, as it indicates how long it takes food to be broken down and start affecting blood sugar levels.
But Spence warns that people should not think that a low-GI diet, said to make you feel full longer, is a fast track to weight loss.
"There is certainly no harm in choosing low-glycaemic index foods. However, they are not a strong factor in successful weight loss."
People still need to ensure they eat appropriate portion sizes. While low-GI food might give a more sustained release of energy throughout the day, it can be calorie-dense.
Rush says: "Usually things with low GI are good for you because they contain things such as fibre, but it depends on the combination they are eaten in."
One size does not fit all
People who are serious about weight loss should find out exactly how much body fat and muscle mass they are carrying. "Find out the truth about who you are feeding." Spence uses a high-tech machine to assess muscle and fat mass, and metabolic rate to assess dietary needs. Versions of the machine are available at chemists.
No two bodies are the same - even two men of the same height and weight can be different, she says. Put an All Black and an overweight man on the same diet and one will lose weight and the other will gain.