1. Your Flabby Friends: Lose 1kg

Palling around with a tubby crowd could be worse that having Rosie O’Donnell as your diet coach.

A study in the New England Journal of Medicine looked at the social networks of 12 067 people over 32 years and found that for every five kilograms gained, close friends of the same height gained on average one or two kilograms.

Instead of making plans to go out for dinner and drinks, catch up with your friends as you sweat side by side on the elliptical machines, play squash or cruise town on your bikes, don’t take "no" for an answer!

2. Credit Cards: Lose 2kg

Your plastic may be affecting more than just your credit score. Visa conducted a study of 100 000 fast-food restaurant transactions and found people who pay with their cards spend 30 percent more than those who opt for cash.

Choose to swipe and you could end up with a double quarter-pounder with cheese and a large Coke instead of a quarter-pounder with cheese and medium Coke.

If you must hit the drive-thru, pay cash. You’re more likely to spend less. Better yet, go home and make yourself a sandwich. It’ll be better for your body and your wallet.

3. The sniffles: Avoid up to 40kg!

Forget feeling the cold. A review in Advances in Food and Nutrition Research found that in animal studies, critters infected with adenovirus-36 – one of 50 human viruses that cause upper-respiratory infections- gained up to four times as much weight as those without it. Scientists speculate that the bug increases the number of fat cells and that it could leave humans lugging around as much as an extra 18 kilograms

Believe it or not, a vaccine to fight the fat culprit is in the works. And adenovirus-36 has already been deactivated in the labs (there are no human tests yet). Until then, wash your hands often, as adenoviruses are typically transmitted through direct contact.

4. Your Meds: Avoid 20kgs

Popping pills for allergies, birth control or diabetes could be widening the rear. According to a report in Pharmacist’s Letter, these pills can stimulate appetite; that can leave you eating and gaining up to 20 kilograms more.

If you suspect a script is to blame for your suddenly bloated belly, talk to your doctor about alternative options for the drugs you’ve been prescribed. Just make sure you don’t swop your current meds without your doctor’s go-ahead.