• Dr Sally Norton


There are all sorts of explanations for why our weight almost invariably piles back on after dieting – leading to despair and ever-decreasing motivation to try again. But, we just keep on trying the same old approach…..and that cycle of yo-yo dieting continues.

So, why does it occur?

Part of it is psychological – we just become fed-up with denial and eventually just can’t resist that doughnut! One mouthful and we feel we’ve blown our diet yet again so set off on an eating frenzy, making up for all those wasted opportunities to eat the food we love. And the weight goes up again.

But it's also physiological, driven by changes in the hormones (chemical messengers) our body produces. Our bodies seem to be pre-programmed to ensure we keep our weight on, in case of famine (somewhat unlikely in the food-laden Western world). And studies have shown that hormonal changes occur when we are dieting - our body thinks we are starving, after all. These changes prompt us to eat more and exercise less to help conserve energy, thwarting our dieting efforts. But, worse still, these changes can persist for months after we have stopped dieting, ensuring that the weight piles back on….and then some.

Another study in the respected scientific journal, Nature, has shed further light on the phenomenon of yo-yo dieting. It seems that our gut bacteria may also play a part. The make-up of our gut bacteria in terms of diversity and types has been shown to vary between obese and slim individuals, prompting speculation that our gut bacteria are involved in our weight control. Scientists studied mice who were put through a yo-yo dieting situation and found that, even after losing weight, their gut bacteria still showed an ‘obese’ pattern for six months or so, seemingly encouraging more rapid weight gain.

Wiping out their existing gut bacteria prevented such marked re-gain, as did giving the mice faecal (poo!) transplants from non-obese mice! A more palatable approach, which also prevented rapid weight regain, was to give the mice substances called flavonoids, which help burn energy and can influence the type of gut bacteria we have. Overall the suggestion was that eradicating unhealthy and promoting healthy gut bacteria could prevent weight regain after repeated dieting.

Where do we find flavonoids so we can potentially break this yo-yo dieting cycle for ourselves?

They are found in fruit and veg. Eat as wide a variety as possible and you may be able to escape the despair of repeated dieting – as well as help your health in a multitude of other ways.

And for more help in escaping dieting misery, join my on my next Weight Loss for Life programme. It's all online - you get 12 weeks of my personal attention to help you lose weight and keep it off for good!


Persistent microbiome alterations modulate the rate of post-dieting weight regain. C. Thaiss et al. Nature December 2016