Chocolate. Chips. Ice-cream. French fries. In my research program at Tufts University most volunteers for our weight loss studies report substantial food cravings for foods like these. There isn't one single food that they all crave, because tastes are different, but craved foods all have one unique hallmark: they are all calorie-dense and typically contain twice as many calories per ounce as other foods. Surprisingly, carbs don't seem to be the important key. The craved foods reported by our volunteers usually contain a mixture of carbs and fat with a little protein thrown in for good measure. Think of the human species as being calorieholics rather than carboholics and you have it about right.

Many people feel bad about being unable to control themselves in the face of their got-to-have-it foods, but, in fact food cravings are completely normal. About 90% of women and 50% of men experience uncontrollable urges to eat particular foods several times a month, and they usually end up giving in... So today's blog is all about the emerging science in this important area and what lessons we can draw now to help with weight control.

Neurologically, the sensation of craving is considered to be a sensation of "need" that we experience as a "have to have it" feeling, arising out of dopamine and b-endorphin circuits in the ventral striatum and other midbrain areas, and is distinct from hedonic pleasure, which is just about loving the taste of food. For example, you may love the taste of fresh ripe raspberries but probably don't crave them. A craving for salty snacks or chocolate, on the other hand, may be enough to drive you out to find at 24 hour store at 10pm.
Typically we have triggers that set us off, such as hunger, stress, particular places, and of course the sight and smell of the item in questions. Because making neuronal connections between disparate pieces of information is the way our brain keeps us grounded in the experience of life, once we learn to eat high calorie treats when other things are going on (like hunger, or baseball games), just experiencing that other event again is often all it takes to set off the crave again and again.

It probably isn't a coincidence that most craved foods are snacks, because probably the real beginning point for cravings is the link our brain creates between the taste of the food in our mouth and its postingestive effects in the body-and of course it will be easier for our brain to link up the taste and digestion for foods that are eaten individually.

Here is how it seems to work based on studies in animals. Say you start having a donut midmorning when you pick up a coffee. Your food brain learns that the taste of donuts fixes the somewhat unsatisfied feeling you have at that time because you get a huge rush of calories into your bloodstream shortly after finishing the last bite. So the next time you get hungry or have a coffee or it is midmorning again you think of donuts! And then later on even thinking about donuts at other times can trigger the neurological chain of events that makes you hungry, and your addiction-circuits ramp up the pressure by giving you sensations of need as well. It all adds up to a craving that is truly hard to ignore. But again, as shown in research in animals, if we could feed you some donuts that were identical in taste to the high-cal stuff, pretty soon you would lose your craving for the taste because your brain would relearn that this flavor actually isn't highly caloric. In psychological terms you would have deconditioned your taste preference for donuts, because the reduced calorie content resulted in weaker postingestive effects.

How do we translate all this good theory into some practical help? Some easy but surprisingly effective treatment options seem to be emerging out of research:

1. Be really vigilant about controlling hunger because hunger (and lack of satiety) is a contributor to cravings. Eating high satiety foods at every meal and snack is one of the important factors here as I discussed in a previous blog ( Whatever you eat, though, hunger control isn't just about what you eat but when you eat it, and in particular having regular meals and snacks with nothing in between and nothing after dinner is also a big help. It takes a few days to get used to not eating at other times, but people adopting the technique for weight loss say it is hugely beneficial and actually not that hard once they get over the first few days.

2. Keep your eyes and nose under control. Avoid looking at and smelling tempting foods, not only to stop cravings once they've started but also to avoid triggering them in the first place. Deliberately look away when you come across foods that are out of bounds. And if you start to smell them, breathe through your mouth!

3. Change your recipes. This is really helpful also. If a taste you crave now comes with fewer calories, more fiber and more bulk, you can still enjoy it, but after a while your brain can "dissociate" this food trigger from the feeling of need and make it a less urgent sensation.

4. Eat craved foods wisely or not at all while you give the above techniques a few weeks to go to work. If craving for a particular food is very hard to control, give up that food for now before trying it again. Some people find it helpful to simply think of a troublesome food-say, cupcakes-as being "not food" or "garbage" or "not a food that I eat." If you decide to bring back a craved food, eat only reasonable, calorie-controlled portions in the middle of satisfying meals, never first or last and never alone.

Finally, there is Forehead Tapping for if you find yourself with a craving and don't want to give in. It's a proven help for cravings developed in Australia, and the theory behind this it is that working memory is small, so it is possible to displace craving thoughts with other mental activities, in this case a simple exercise that can be done anywhere. Just place the five fingers of one hand on your forehead, spaced apart. Tap each finger in turn at intervals of one second while watching each one carefully as it taps. Keep repeating the exercise until the craving sensation disappears! Alternatively, tell yourself "Not today" or "Hold on" and wait 15 to 20 minutes while you distract yourself by calling a supportive friend, drinking a full glass of water, chewing a piece of sugar-free gum, brushing your teeth, going for a walk or meditating. Keep a record of whatever thoughts and feelings you have leading up to cravings so you can recognize (and avoid) particular behavior chains that are a problem for you.

Will it work for you? There are no randomized controlled trials yet for the effectiveness of craving treatment, but in a group of people being tracked who are using my Instinct Diet menus to lose weight, 90% report that cravings completely disappear. While research studies have a chance to provide hard numbers on craving reduction, you may wish to get started with some of these ideas on your own and see how much healthy changes can help.

Susan B. Roberts, PhD is professor of Nutrition and professor of Psychiatry at Tufts University, Boston, MA, and also author of The Instinct Diet (Workman, 2008). A group of users of the diet in Boston have lost an average of 16 pounds of weight and 2 clothing sizes while on the 8-week program, and 90% report a complete elimination of food cravings. For more information on The Instinct Diet see

About the Author

Susan B Robert

Susan B. Roberts, Ph.D., professor of nutrition and professor of psychiatry at Tufts University, is an expert on nutrition and weight control.

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