You might find it a bit depressing being told your best efforts are most likely to end in failure.

Auckland doctor Robyn Toomath spent years telling her diabetes patients to lose weight only to have them fail despite their best intentions.

Eventually she stopped altogether and her book, Fat Science, explains why.

Radical as it might sound Toomath says individuals shouldn't be held responsible for becoming fat, or obese.



"It's not appropriate to consider body size as being within our personal control when genetics and the environment in which we live has such a powerful effect."



Toomath says some people are genetically pre-disposed to weight gain and in an environment packed with fatty, sugar-soaked food, it is inevitable they will lose any battle of the bulge.

Maarten Holl/Fairfax NZ Anti-obesity campaigner Robyn Toomath.

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Rather telling the one in three over-weight and obese Kiwis to "just do it", Toomath wants the government to take some action to make healthy eating easier.



Blaming individuals for obesity lets governments off the hook and is a "distractor", she says.



"We need to be getting on and using fiscal measures to change the default environment so that it's favourable to healthy eating and while we can keep pointing the finger at the over-weight individual then they have been able to get away with this."



Fat Science is essentially a challenge to the widely accepted wisdom that a bit of self-discipline is all that is required to lose weight, the kind of thing that is driven home on reality weight loss TV shows by star trainers to their hopeless charges.



Science shows it is largely futile to achieve long-term weight loss in an "obesogenic" environment but individuals continue to blame themselves for failure, Toomath says.



"They don't understand the science well enough to realise there are drivers, largely beyond their control, which dictate their body size and so people are harsh on themselves, people believe it's their fault and...they're gutless or lazy, people talk about themselves in this way."



For those looking for an uplifting and inspirational "answer" to personal weight issues, Toomath's book will probably not deliver.

Warwick Smith/ Fairfax NZ. Toomath is taking a stand against canteen food at schools.

In fact, some may even find it a bit depressing being told their best efforts are most likely to end in failure.

"I hope not, I hope it provides them with comfort," Toomath says.

She hopes the book will inspire people to take action on the things they can change, that will help combat obesity for everyone, including themselves.

"... instead of controlling your self-control, it's about controlling the environment - to the extent that you can.

"You could decide I'm fat, my kids are likely to be fat, I'm on the board of trustees at my school so I'm not going to have them selling chips and giant cookies in the canteen, I'm going to protect the kids and I'm going to suggest that they just sell healthy food."

Fat Science also takes aim at exercise - often seen as the answer to obesity.

"I think exercise is great and there's no question about the value of exercise...but it comes down to the same thing - can you prescribe exercise for people and expect them to do it year in year out to the level that would keep their weight normal?"

While people become passionate runners, cyclists or paddle boarders for a time, Toomath says they don't usually keep at it.

"... it's rare you get someone who decides this is going to be part of their life year in year out…"

In the book, Toomath says there are lots of short-term studies that show a combination of calorie restriction and moderate exercise work to reduce weight, however it is unlikely the results can be transferred to the general population.

Perhaps more importantly, she says success at 10 months is no guarantee of long-term weight loss.

Instead she supports "walkable cities" and workplace design which facilitate physical activity.

While she would advocate for a tax on sugar sweetened drinks, she says there are many other things that could be done to help people live healthier lives.

Marketing science used by supermarkets to manipulate shoppers to buy unhealthy food and drink could be taken over for good, Toomath says.

"Why don't we use product placement science to persuade people to eat healthily? If we really set out to change the patterns of behaviour to get people to eat more healthily - you could do a huge amount."

Fat Science is published by Auckland University Press. RRP $29.99.

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