The sign
You're finding hair everywhere - except on your head.

The likely culprit
Not enough kilojoules.

"Dipping below 4000kJ a day deprives your body of the energy and nutrients it needs to regenerate hair cells," warns nutritionist Cindy Moore.

The fix
Never drop below 7500kJ a day, Kojak.

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The sign
You're snapping at colleagues.

The likely culprit
A low-carbohydrate diet. Researchers at the Massachusetts Institute of Technology in the US found that cutting carbs can lower levels of the mood-boosting chemical serotonin over time.

The fix
Eat fibre-rich wholegrains with every meal, advises study author Judith Wurtman.

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The sign
You can't concentrate.

The likely culprit
Skipping breakfast. Researchers at Bristol University in the UK found that people who dodged their cornflakes had focus problems. "After a night of not eating, you need to give your brain glucose," according to Moore.

The fix
Eat within an hour of waking. Rushed? Make it easy. A handful of almonds and an apple.

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The sign
Too much toilet time.

The likely culprit
A diet low in fibre or an intolerance to dairy.

The fix
Slowly boost your fibre until you're eating roughly 35g a day from wholegrains, vegetables and fruit. Still crook? Skip dairy for a week, then have milk or cheese. If you're lactose intolerant, you'll find out fast.