My latest blog post for WedMD’s Real Life Nutrition explores why fat-free, sugar-free and other so-called diet foods are not always the best choice. Hope you’ll check it out.
In my post, I highlighted a fascinating study that may make you think twice about always defaulting to the low-fat snack or sugar-free dessert. To me, it really reinforced why we should be approaching food with a sense of pleasure – not guilt, fear, or regret. If you’re in a constant search for the best “diet” food, you may never feel fully satisfied and may simply keep eating to fill up the void. And that’s what this Yale study demonstrated.
Alia Crum and colleagues gave participants two different types of milkshakes – one was a “diet” version, described as fat-free, no added sugar, and low-calorie. Its label promised “guilt-free satisfaction.” The other shake was the indulgent version, described as high-fat with 620 calories. Its label touted “decadence you deserve.” Guess what? They were the exact same milkshake (380 calories), but the participants didn’t know that.
When the participants drank the “guilt-free” milkshake, their bodies responded much differently than when they consumed the indulgent shake. Even though the nutrient profiles of the shakes were identical, the diet shake was less satisfying and the researchers had blood samples to prove it. They measured levels of ghrelin, or what’s often referred to as the “hunger hormone.” When your blood levels of ghrelin are high, it sends signals to your brain to say you’re hungry. As you eat, ghrelin levels fall, which reduces your appetite and makes you feel full. Ghrelin levels may also influence your metabolism: low levels speed up your calorie burn, while high levels may slow the burning of calories.
After drinking the indulgent milkshake, the ghrelin levels of the participants dramatically declined. Yet, when they were given the diet milkshake, ghrelin levels stayed stable – indicating that their bodies did not get the same signals of fullness. That’s rather astounding to me. Participants drank a shake that had the same amount of calories and fat, but their perceptions of what they were about to drink altered their body’s physiological response. When we think we’re getting a “diet” food, we anticipate feeling deprived and our body reacts with more hunger and less satiety.
To me, this is even more evidence to ditch the diet food, and keep pleasure a part of the picture at mealtime. You may find yourself eating less and enjoying it more.
image courtesy of goldrushdirect on flickr