We've all had those days when we're just too tired or stressed to work out. The thought of pushing your body at the gym holds little appeal after an extra-long day at the office or a night spent caring for a colicky baby. Even if we can force ourselves to go to the gym, it can still be tough to slog through the workout.

 

But did you know that your mind may be the reason you don't feel like pushing your body? According to a new study out of the Diabetes, Endocrinology, and Obesity Branch at the National Institute of Diabetes and Digestive and Kidney Diseases, it could be the fault of a little neurochemical called dopamine.

 

 

Dopamine is the chemical responsible for stimulating your brain's pleasure and reward centers. Do something that makes you feel good, and it's dopamine that's giving you the feelings. Not only does dopamine help us feel the reward, but it's the thing that encourages us to work toward them.

 

To determine the effects of dopamine on motivation to exercise, researchers fed a group of eight mice a high-fat diet for 18 weeks. Compared to the control group (mice who ate a normal diet), weight gain increased by the second week. By the fourth week, the obese mice moved less, and what little movements there were tended to be slower.

 

The researchers examined the D-2 type receptors (which pick up dopamine signals) and found that the obese mice had less sensitivity to dopamine. This reduced sensitivity to dopamine didn't cause their weight gain—it was simply a side effect of their obesity, which led to inactivity.

 

Let's be clear: dopamine, or a lack thereof, isn't going to make you gain weight. Only a high- fat/high-calorie diet and a lack of exercise will cause that particular problem. But, as a result of the weight gain, you may find it harder to move around. Your lack of willpower to exercise is very likely due to the reduced dopamine sensitivity, a side effect of obesity.

 

 

So let this be a lesson. Even if you don't feel like working out, you've still got to do it.

You don't need the reward chemical to tell you that exercise is good for you—you know it is. You also know it's the only way to lose weight and get back to a healthy weight. Don't let reduced dopamine production caused by obesity lead to you quitting or cutting back on your workout efforts. Keep up with the dieting and exercise no matter how you feel.

 

Reference:

1. Danielle Friend et al., "Basal ganglia dysfunction contributes to physical inactivity in obesity, Cell Metabolism," Doi 10.1016/j.cmet.2016.12.001, published online 29 December 2016, abstract.

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