Q: I normally eat healthy foods but sometimes I'm hit by cravings. I end up succumbing to the candy and fattening foods that I know I shouldn't have. Why is this and what can I do about it? A: We're driven to eat by more than just hunger pangs. And for many people, it's hard to resist the lure of fast food, sweets and snacks.

Some people attribute cravings for certain foods such as meat, for example, to the body's instinctual need for certain nutrients, like protein, that it is lacking. This has not been proven, and it seems unlikely that urges for what people most commonly cravefoods like potato chips, french fries, sodas and candyare signs that the body is low in saturated fat, salt, sugar and artificial flavorings and preservatives!
The psychological stimulus to eat can be powerful enough to override your pure physical needs. If you're with a group of friends having dinner, for example, it's easy to eat more than you might alone because of the social aspects of sharing a meal. And who, when they are already full, hasn't made room for “a little more” when a tantalizing dessert arrives.
Although food has not been proven to be addictive in the same way as cigarettes, there do seem to be strong impulses to desire certain processed foods. Can you imagine craving a red bell pepper in the same way that you might yearn for a Coke, a burger or ice cream?
 

Sweets and fats may be especially tempting because humans haveinnate preferences for them and some people may have stronger genetic predispositions than others. An attraction to these highly palatable foods makes sense in terms of survival because these foods tend to have more energy (calories.) Of course, in an environment where food is abundant, this tendency can lead to overeating. Some people worry that snack food manufacturers capitalize on this weakness and purposefully develop foods to be addictive by researching and concocting products with specific ratios of fat, salt and sugar that are hard to resist. (Millions of dollars spent on advertising also trigger your lust for these foods.)

There is also evidence that some people perceive certain foods to be a reward, which may increase a craving for those foods. Brain scans have shown that some obese people experience greater activity in specific areas of the brain that are related to reward and addiction.
Whether this is purely biologically driven or something learned is unclear.
But a fondness for foods can develop from events associated with them. A child whose family had pleasurable Sunday morning breakfasts with puri & parantha may grow up and associate these items with the warm, feel-good sensations they may arouse. Someone who is an emotional eater and seeks food for comfort when upset may be evoking a similar response.
Women often report an increase in pre-menstrual cravings. During the week or so before your period, estrogen levels drop and the body uses a few hundred extra calories, which may result in more snacking. Women who experience the PMS-related blues may also be drawn to high-carb treats that boost brain serotonin levels that can improve mood.
Of course, a highly likely explanation for cravings is that you simply need more energy. If you're not fueling your body in regular intervals, you may be driven by a need to eat more calories and the most easily available and easily digestible items are going to be especially tempting.

And don't worry. Even if you do eat more than you'd like on occasion, as long as you are physically active and eating nutritious meals most of the time, you shouldn't gain weight, since fluctuations in energy intake over the course of the month will all balance out.