This could be why you're fat - 5

TIGHT WAISTBAND, BLOATED FEELING

COULD BE: Food intolerance.

Other tell-tale signs include flatulence, nausea, diarrhoea and discomfort after eating, possibly combined with fatigue and aching joints.

If your body is intolerant to certain foods, it finds them difficult to digest and they will stay in the digestive tract partially digested, bubbling and fizzing with bacteria.

Wheat and milk are common triggers. According to GP Dr Rob Hicks, intolerance to the lactose in milk and dairy products is ‘hugely under-diagnosed’.

He adds: ‘I believe that many people who have been told they probably have IBS (irritable bowel syndrome) may, in fact, be lactose-intolerant.’

WHO'S AT RISK? We all produce less of the enzyme lactase (which should break down the lactose in dairy products in the gut) from the age of two. In some people, the levels drop faster than others.

Lactose intolerance is more common in older adults.

WEIGHT-LOSS SOLUTION: Keep a food diary of everything you eat and drink, including any medication, and, in a separate column, jot down details of symptoms.

According to Lindsay McManus, spokesperson for Allergy UK, food intolerance symptoms may be delayed (unlike allergy symptoms, which can be immediate). But after a few weeks, you may begin to see a pattern emerging.

If you identify possible triggers (wheat, milk and eggs are the most common intolerances) experiment by excluding one (only one at a time) from your diet for a few days.

‘If you have an intolerance, you should feel better within one to two weeks,’ says Ms McManus.

‘You can double check by putting the food group back to “challenge” your intolerance. Any reaction will normally be swifter and more extreme than before.’

If symptoms are severe, take your food diary to your GP and ask to be referred to a dietitian, who may supervise an exclusion diet and advise on a replacement to ensure nutritional balance.