Slate Magazine thinks so. There is some solid data support that diets work mainly because of the placebo effect. That’s great news. Design a diet that is safe. When it comes to building muscle mass, try a well designed placebo experience first before getting those steroids from your friend. Short excerpt from slate here:

For years, nutrition experts have been trying to figure out the best diet for people who want to lose weight and have more energy. They haven’t been terribly successful. Very few innovations in that field have lasted (beyond eating less and exercising more). Of course, that hasn’t stopped us from trying: There’s the Atkins diet, the all-cabbage diet, the morning-banana diet, the werewolf diet, the Israeli army diet, the Master Cleanse, the Zone, the charcoal cleanse, the alkaline diet, and the baby-food diet, and (my favorite) the Hollywood cookie diet. There’s even a diet that says you will eat less and shed pounds if you just plug your nose while you eat.

While all of these make impressive claims, science has shown again and again that dieting just doesn’t work in the long-term. Most people either don’t lose the weight or see it boomerang right back (for others, the result of dieting is an eating disorder). But still, we cling to diets because we think they will work—or because often, for a short time, for some of us, for that friend-of-a-friend, they do.

f no diet has turned out to be a silver bullet for weight loss, then what could explain why some of them at least seem to work, at least for some time? In looking at our rampant dieting culture, I realized that there are a lot of elements that remind me of the placebo effects we see in other parts of our lives. And this got me thinking: Perhaps it’s not the contents of the diet that matters. Perhaps it’s simply the act of dieting. Is it possible that, rather than the specifics of the food regime you undertake, it’s the mere act of starting a diet—any diet—that makes you thinner? Could it be that the inherent placebo effect that comes with any diet is what’s causing you to lose weight?

The connection between brain chemistry, eating habits, and weight is nothing new. Our decisions to eat are based on brain chemistry, and the results of those decisions tend to affect our size. We know that stress hormones generated by dieting and other forms of starvation affect how our bodies process fat. Some studies even suggest that deficiencies in certain mood-moderating brain chemicals shape which junk foods we prefer: People with low dopamine crave sweets, those lacking the neurotransmitter acetylcholine crave fat, and those without serotonin try to eat all the starch they can get. So brain chemistry and metabolism are intimately linked.

But could the act of believing that what we are eating will cause weight loss actually be enough to trick our bodies into shedding pounds?

The the rest of the article here