We caught up with internationally-renowned obesity researcher and clinician, Prof Joe Proietto, to discuss the global epidemic of obesity and what we actually need to do to achieve a healthy body weight.

Transcript of Interview with Prof Joe Proietto and Dr Catherine Bacus

 

Dr Catherine Bacus:

“So welcome and thank you for joining us Professor Proietto, my name’s Dr Catherine Bacus and I’m here today with a professor who is an internationally renowned obesity researcher and clinician and is here to answer a few questions for us today. So, I guess one of the main questions we have is – what causes obesity? Why is there such an epidemic of weight gain at the moment?”

Professor Joe Proietto:

“There is very strong evidence that obesity has a strong genetic predisposition and this comes from identical twin studies and from adoption studies. Naturally you need the correct environment to have these genes express what they’re meant to do and that is to help us store energy. So the recent epidemic is a combination of the fact that there has always been people that are genetically susceptible but the environment wasn’t there and now there is.  And also potentially epigenetic change, which means environmental factors that can alter gene expression.”

Dr Catherine Bacus:

“Yes that makes sense. So for our patients who are really wanting to lose weight to improve their health, what is the best way for someone to go about this?”

Professor Joe Proietto:

“I think, to lose weight you need to reduce energy intake below energy expenditure and that makes sense and there are any number of ways of reducing your food intake but in 2014, we published a study in the Lancet Diabetes Endocrinology Journal where we showed I think the best way to lose weight. You see, the problem with the traditional diet approach is that as you lose weight, you become hungrier for reasons that will become obvious.”

Dr Catherine Bacus:

“I think most of our patients can attest to that.”

Professor Joe Proietto:

“Exactly so what we did was we randomised a group of patients into rapid or slow weight loss and we found that it made no difference to regain. It’s not true that the quicker you lose it, the quicker you put it on. But we found that we had more success with the rapid arm of the study compared to the gradual arm. The secret of the rapid arm was not only did they eat less but they were ketotic. In other words, we designed a diet to be nutritionally complete and ketogenic. Now ketones are products of fat burning. When the liver is burning fat it releases ketones into the blood stream and they suppress hunger two ways, by directly acting on the brain and then also by changing the hunger hormones.”

Dr Catherine Bacus:

“So that means that it makes it easier for patients who are on a lower energy diet to stick to it because their hunger is suppressed.”

Professor Joe Proietto:

“Correct and that’s why in that study we had eighteen people out of a hundred drop out of the gradual arm but in the rapid arm which was ketotic only three out of a hundred dropped out.”

Dr Catherine Bacus:

“It makes sense why, doesn’t it? Okay so can you help us to understand why many people can lose weight but why do we all seem to regain it? How can we be successful in the long term for keeping weight off?”

Professor Joe Proietto:

“This always perplexed me. I couldn’t understand why someone who’s motivated loses weight and then puts it back on again. So we did a study published in 2011 in the New England Journal of Medicine where we measured these hunger hormones that we have in our blood. We have ten hunger regulating hormones in the blood, which interestingly there’s only one that makes us hungry and nine that take our hunger away”

Dr Catherine Bacus:

“So that one is very powerful?”

Professor Joe Proietto:

“Well no, it means that it’s actually very hard to stop the brain looking for food and we measured these before people lost weight, after they lost weight and a year later and what we found was that the hormone levels nearly all change in a direction to make you more hungry and then we found that they stay there a year later. Then we had evidence at three years, now there’s evidence at six years which means that because the weight is genetic, the body does not give up trying to get you back to your genetic set point.”

Dr Catherine Bacus:

“Which is good if we’re at a time of famine but not so good in this era.”

Professor Joe Proietto:

“Correct, our modern environment is up against our biology that was really optimised when we didn’t have agriculture, when we didn’t have the industrial revolution and science.”

Dr Catherine Bacus:

“So then what would be your top three tips for our patients who are wanting to keep their weight off in the long term?”

Professor Joe Proietto:

“Right so after achieving weight loss because you don’t expect patients to be ketotic the whole time because it’s very hard to stay away from carbs in our society then what we advise patients to do is following going back onto ordinary food, they need to be mindful of what they put on their plate, they need to be aware of what they’re weight is doing so it requires regular weigh ins, they need to do exercise vigorously or you exercise to your capacity – at least an hour a day and then despite all of that, if they regain two kilos then they have to go back on the ketotic diet. And that’s a strategy for maintaining weight without medication. The problem is that it eventually grinds you down and so my belief is that while you don’t need medication to lose weight, you probably need it to keep it off.”

Dr Catherine Bacus:

“To overcome some of those hormonal signals that are driving up hunger and increasing our desire for food.”

Professor Joe Proietto:

“Correct, yes.”

Dr Catherine Bacus:

“Okay makes sense. Well thank you for your time today, thank you for helping answer some of the questions that we have and for helping us to understand why it is difficult to lose weight and what we can do about it and how we can live a healthier life with greater wellbeing.”

Professor Joe Proietto:

“Pleasure, thank you.”

22 February, 2020

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