Food & Nutrition

Do diets really work?

Dr Michelle Celander, Director of Program and Science at WW, talks us through some popular diets, whether they’re worth trying and the secret to keeping the kilos off for good.
Published 20 February 2019

What is the best way to lose weight?


“If you think about diets in terms of short-term weight loss, they actually do work. The problem is keeping it up for the long term.”

“A major factor in a diet working in the long term is sustainability of the changes you’re making. One question to think about is, ‘Can you see yourself doing this in a year or two from now?’ And if you can’t see yourself being able to sustain this way of eating or living, then it’s destined for failure. Even if it works in the short term to help you get rid of some kilos, they are likely to come back.”


Diet vs a healthy eating program

“One of the hallmarks of a diet is that they are restrictive and likely to exclude things. They look at groups of foods such as dairy or grains and categorise them as ‘bad’. We need to look for programs that focus on what you can eat rather than what you can’t. A sustainable program incorporates the principles of healthy eating, such as eating more vegetables, eating lean protein, incorporating healthy fats and being mindful of portion sizes. Those fundamentals are what will really help you to stay full, get healthier, and ultimately lose weight and keep it off. A sustainable program also allows you to do the things you love. It’s about finding a way of enjoying eating healthy food that suits you and that you can do for life.”


Ketogenic diet

“The keto diet is all about minimising carbohydrates and upping your intake of fats. The theory behind this way of eating is that it causes your body to create ketones, which become your body’s go-to source of energy. Some people can do well with this approach but one thing to watch out for is that people tend to feel lethargic rather than full of life on this diet. Also, it’s quite difficult to eat out, travel and socialise when you’re trying to follow such a restricted eating pattern.”

>Read more more about the keto diet



“This is a similar type of approach to using food supplements. It’s not really novel in that we’ve seen lots of these types of programs come out where you stop eating regular food and drink shakes instead. Whilst these drinks are filled with vitamins and minerals, the fact that you’re not eating real food again brings back the question, ‘Is it sustainable in the long run?’ Nutrition is highly complicated in terms of the way different foods interact with each other and I don’t think anything can replace eating a mix of real foods. It’s not an approach I’d be recommending.”


Intermitent fasting

“If you’re including vegies, lean protein, healthy fats and good grains on the days that you are not fasting, then eating less for some days of the week may be an approach that suits you. While there’s not much evidence yet to demonstrate whether fasting is safe in the longer term, the question is, is it harmful to eat less for shorter periods of time? Humans have certainly been fasting throughout history. As long as the fasting is for short periods, then it may be an approach that somebody could maintain. But it is about sustainability—it’s not about doing it for a couple of months to get a few kilos off because as soon as you get back to eating every day of the week the weight will come straight back on again.”

>More about about fasting


Juice cleansing

“In short, no. A juice cleanse is usually related to detoxing and it’s important to remember that we have a very clever body that is designed to detox for us. On a juice cleanse you’re very low in protein and your blood sugar level swings because you’re not getting enough complex carbohydrates or fat into the body. You’re also not getting enough protein, so you could be using muscle mass as a source of fuel. Your muscle mass guides your metabolism, and with less of it you’re more likely to put on weight. Ultimately, while fruits and vegetables are critical to good health, it’s important to remember that with a juice cleanse you’re drinking huge quantities of them, in volumes that can be excessive.”

>More about detoxing


The verdict?

“Fad diets are generally not nutritionally balanced and may leave us feeling run-down. They can be ineffective because they can become boring and we can’t sustain something that’s dull long term. A sustainable diet needs to have us saying, ‘Wow, I feel good’. That’s a positive feedback cycle that will motivate you to persevere.”