Following a so-called detox plan - often popular in January - is a waste of time and money, scientists say.
The scientists advise drinking ordinary tap water
They say many supplements do not have any effect and the body can recover from Christmas excess on its own.
The detox business - which includes diets, tablets and drinks said to flush out toxins - is said to be worth tens of millions of pounds.
But the scientists from the Sense About Science organisation say water, fresh air and sleep is all that is needed.
The term detox is meaningless as the body is perfectly capable of clearing out harmful substances, they add.
The gut prevents bacteria and many toxins from entering the body, while the liver contributes to breaking down harmful chemicals which are then excreted by the kidneys.
Tap water rehydrates the body and a good's night sleep will leave people refreshed, the scientists said.
They dismissed detox tablets, socks, body wraps, diets and eating Nettle Root extract or drinking herbal infusions or "oxygenated" water in a bid to make natural procedures more effective.
"They waste money and sow confusion about how our bodies, nutrition and chemistry actually work," they said.
The high street chemist Boots, which sells detox products, maintains they have a role to play when combined with a healthy diet and exercise.
US research last year also concluded that detox diets do no more than the body's own natural system to get rid of toxins.