Tempted to go on a diet to kick-start your 2016 weight loss mission?

In an ideal world, we’d all go for the sensible, slow and steady approach: a healthy balanced diet and regular exercise – good habits we can keep up for life. Instead we often fall into the starve/binge cycle, which we all know can so easily result in unhealthy yo-yoing.

And that’s not the only negative side effect of going on a crash or fad diet – your breath might suffer too.

According to a recent survey by UltraDex, less than 15% of people are aware that skipping meals can cause halitosis. High-protein and low-carb eating plans can also be notorious for causing bad breath.

Still tempted by that promise of a quick fix? Here are five other unwanted side effects associated with crash and fad diets:

[Related story: Celebrity diet fads to avoid]

Fatigue and tiredness

Food is what gives us energy. So if we don’t get enough of it, naturally our energy supplies can run low. This can be linked with simply not getting enough calories to function effectively, or missing out on essential vitamins and minerals.

“Some diets recommend as little as 1,000 calories or less each day. If you partner this with exercise, it's simply not enough food and you will likely suffer tiredness as well as the possibility of nutrient inadequacies,” warns Rob Hobson, head of nutrition at Healthspan.

“Diets that promote the exclusion of major food groups can also leave you feeling tired, such as carb-free diets.”

Poor sleep

Ironically, while being hungry might leave us battling tiredness, it can also mean we struggle to sleep well. “There are often diets that recommend not eating after very early evening, sometimes as early as 6pm. If you're going to bed late, then there is a good chance you're going to get hungry, which may cause trouble sleeping for some people,” notes Hobson.

Mood swings

Being ravenous – and possibly a bit sleep-deprived – is a sure-fire recipe for being in a bad mood. If you’re dieting, and suddenly find yourself turning into an angry, impatient, irritable dragon who just wants to snap at everybody, chances are your body is trying to tell you something: feed me.

Clinical Nutritionist Suzie Sawyer suggests: “Try to eat fresh, whole foods and avoid sugary snacks and too many caffeinated drinks which upset your blood sugar balance and negatively affect your mood.”

[Related story: Revealed: The diets that really work – and the ones that don’t]

Poor concentration

Just as our bodies need proper nourishment, so too do our brains. If you’re lacking in vital nutrition – and also low on energy and tired – then it’s little wonder that you won’t feel as sharp as usual. This can make keeping up at work difficult, and take the joy out of social interactions. Is it worth it?

Digestive problems

A healthy gut needs regularity, and restricting your food intake too much can result in things becoming sluggish. Diets can disrupt digestion in other ways too; for instance, cutting out whole foods groups might mean you don’t get enough fibre, leading to constipation, while over-consuming fruit and veg – with not enough solids, starchy carbs, protein and wholegrains – can cause diarrhoea.

“One problem is skipping meals, which may affect digestion,” adds Hobson. “It's one less opportunity to properly nourish the body and that includes fibre, which most people already eat too little of. Also, skipping meals, then eating - or even worse, binging - after a long period of not eating, can leave you feeling heavily bloated.”

Do you think diets are a bad idea? Tell us about your experiences in the Comments section.