When it comes to weight loss, everyone is looking for the silver bullet. Add in ageing and all of a sudden the tricks you used to lose a couple of kilos when you were 20 years old don't work anymore.
Could hormones be the key? Stacey Morrison finds out if hormone diets are healthy or just a hoax.
Listen to Healthy or Hoax with Stacey Morrison
Follow Healthy or Hoax on Apple Podcasts, Spotify, iHeart or wherever you get your podcasts
Kadambari Raghukumar, host of the RNZ podcast Here/Now, was sent a link to a diet marketed as a 'metabolic renewable programme' and thought she would give it a go.
"It sounds very attractive. I mean, how do you not click on that, right, 'metabolic renewal'? Renew is the most attractive word you can put out there," she says.
Raghukumar was asked a series of questions about her current weight, daily stress levels and how much exercise she does, with the end promise that she would find out how her hormones were working and then be given a diet that would kickstart her metabolism and help her lose weight.
Raghukumar was disappointed in the results, which labelled her a 'Hormone Type 1'.
"It said 'Hormone Type 1' is mixed signal hormones. But hang on a second, isn't everybody mixed signals at some point in their life? Your body's always throwing different things out to you. That just sounds a little too vague. I couldn't make much sense of it."
Raghukumar was told that this hormone type meant she could find it easy to lose weight and gain more energy.
"But it also told me certain things that I, to an extent, already had known," she says.
"It gave me the rundown as to how you can reduce cortisol levels, which is invariably related to stress and I found that quite, just really generic. It doesn't really take a test to know that about anybody's life really, the more stressed you are, the more likely you are to gain weight."
In the end, Raghukumar decided the diet wasn't worth it.
"I stopped before I could even get to the stage where I was going to subscribe to the programme.
"I just thought, 'do I have to sit here and watch an infomercial of this'? A man with a very glamorous name for a doctor talking to me in a very, very heavy American accent telling me what I can do to change my life? I couldn't really follow through with it."
Could a hormone diet work?
Professor Wayne Cutfield, an endocrinologist from the Liggins Institute at the University of Auckland, admits the concept of a hormone diet sounds cool. He explains that hormones are impacted by weight. If we get the balance between food in and activity out wrong, we pile on the weight and then a bunch of changes occur.
"We make insulin to help us regulate our blood sugar and our fat and our protein levels. And as you get bigger, it doesn't work very well," Cutfield says.
"So you have to make a lot of it. And it's called insulin resistance, and that can eventually lead to type 2 diabetes, for example.
"And for women, if they put on large amounts of weight, it can cause their whole menstrual cycle to become completely disrupted, their whole axis from puberty hormones in the pituitary down to the ovaries can be quite disrupted and it can lead to very irregular periods and a condition called polycystic ovarian syndrome."
Professor Cutfield says there are other hormones that relate to appetite and satiety (feeling of fullness), but the key one is insulin. If you can lose weight, you can often get a significant correction in those hormone imbalances.
But Professor Cutfield does not agree that balancing your hormones makes losing weight easier and he says the idea of a hormone diet is slightly illusionary.
"When I first heard it, I thought, 'Oh, does it mean you're taking hormones or does it mean that there's some cataclysmic shift in your hormones that you are engineering?' And the answer is no."
Cutfield says the components of the diet are sensible lifestyle choices, which include: eating more leafy green vegetables and fruit, reducing your intake of red meat, refined carbohydrates and sugar, and increasing your activity levels.
"I mean, they're all lifestyle changes that we should all espouse too. Unfortunately, humans are hedonists and we don't like to exercise and we like to eat the things that are bad for us," he said.
He also warns that sticking to that programme alone is unlikely to help you lose weight unless you eat less.
"That fundamental axis, the seesaw between how much you eat and how much energy you lose to activity. It's a balance."
Professor Cutfield isn't sold on the idea that we have a hormone "type".
He says that suggesting there are particular hormone profiles across a whole bunch of hormones is a little false.
He's also suspicious about the ability to come up with a particular profile through an online quiz.
"It might make some assumptions, for example, if you only sleep a few hours a night, your stress hormone levels might be a bit more elevated and if you sleep better, they could improve," he says.
He doesn't believe that a diet based on properly measured hormone levels would necessarily work either.
"The diet that will work if you have a weight-related problem is eat less food. You can tweak and refine. You can do a five plus two. You can eat slightly less carbs. I mean, they sort of help a bit. But the heart of it is we've got to eat less.
"There is no fix where you can live badly and lose weight."
Ageing only compounds these issues.
"If you look at the natural progress through middle age, several things happen to us as we age. The first thing is our spines slightly compact and we lose several centimeters and we tend to have an increase in abdominal fat.
"If we look at the distribution for a given weight of body fat, there's a bit more about around the middle for men and women."
He says that effect can be slightly exaggerated for women with the loss of estrogen. But it still comes down to that balance of energy in versus energy out.
"If you get that out by a sandwich a day and look at it over time, then you realise you've had quite a big net gain," he says.
"If you get the balance out, you get this creeping phenomena. And of course, ageing is associated with time and the opportunity for the creeping phenomenon to occur."
Professor Cutfield says hormone diets are misleading and make the weight loss story more complicated than it needs to be.
"It’s easy to get tangled up in the detail and the complications of what hormones are changing," he says.
"Attack the root issue, which is lose some weight and if that's the focus, all good will follow."