I went to the gym on the morning of January 2 to find it as busy as a weeknight at 5.30.
"Everyone's made their New Year's resolutions," said the trainer. Everyone, it seemed, had decided to atone for the sins of their holiday eating, drinking and lazing with an extra-hard workout.
It's natural to feel like this after the summer break - a time of indulgence and celebration when we break from our everyday habits and kick back, often with a "what the hell, it's Christmas" attitude.
It's the hangover we feel after this - the feeling we need to make good, to re-set - that is perfectly and expertly exploited by a whole industry devoted to helping you detox, cleanse or flush away the toxins accumulated in the holidays.
Tempting as it is to buy into this idea - especially if we're feeling sluggish after a period out of our normal routines - it is really nothing but clever marketing, effective at cleansing wallets and not much else.
The language of the "detox" is fascinating.
It's science-ish. Terms that sound technical and medical are used to persuade us toxins accumulate in our bodies and need to be cleansed from our systems so we can function properly.
An array of vague symptoms are attributed to these toxins - ranging from headaches to skin problems to weight gain - and the detox products and diets promise to deal to these and make us feel and look better.
It's probably not news that our bodies do not need to be artificially cleansed. We have a complex and sophisticated in-built detoxification system made up of our skin, kidneys, lymphatic system, gastrointestinal system and liver.
Although detox advocates will assert that toxic sludge-like build-up accumulates in our colons, or that toxins are accumulating in our kidneys and livers and these organs need to be flushed out or cleansed periodically, like you'd change a water filter, this is not how our bodies work.
The blog Science-Based Medicine puts it like this: "The liver is self-cleansing - toxins don't accumulate in it, and unless you have documented liver disease, it generally functions without any problem. The kidney excretes waste products into the urine - otherwise that substance stays in the blood.
Anyone who suggests these organs need a 'cleanse' is demonstrating that they don't understand basic anatomy or physiology."
Anyone who suggests these organs need a 'cleanse' is demonstrating that they don't understand basic anatomy.
The drastic effects people sometimes feel from cleanses or detox diets are generally not from toxins being eliminated.
They're from a combination of eating less than usual and the laxative ingredients often found in detox supplements. Weight-loss is likely to be water and temporary.
But what if you do want to "re-set" for the new year?
I'm a fan of the idea of a "re-health" rather than a de-tox. Try adding things to your diet rather than taking them away. Add a lot more vegetables; drink more water; add plant-based protein and true whole grains. Add more colour.
Doing these things will automatically displace junk food and alcohol and you won't feel deprived. And the effects will likely last into the future, too.