One of my overweight patients recently asked me if it mattered whether she used up the last 250 calories of her day by eating 250 calories’ worth of M&Ms versus chicken breast.

The short answer to this question is that in basic terms, it doesn’t matter a whole lot where the calories come from. A calorie is simply a unit of energy (defined: the amount of energy required to raise 1L of water by 1 degree C). Whether she eats 250 cal of M&Ms or chicken breast, the key to successful weight loss is about having that 500 cal deficit per day, which will result in 1lb of weight loss per week.

The long answer is: No… BUT:

1. You are more likely to feel full from eating 250 cal of chicken (= about 1 medium chicken breast), compared to 250 cal of M&Ms (=55 plain Ms). If you feel full, then you are less likely to go over your limit and consume MORE calories later in the day, or the next day. This is because protein (chicken) is more satiating than carbs (M’s are composed of carbs (sugar) and some fat).

2. There is slightly more energy burned in the digestion of protein than in the digestion of the simple sugars in the M’s, but this effect is probably not as important as #1 above.

In the big picture, I always advocate for making healthy food choices and eating a balanced diet… but it is sometimes better in the long run to allow yourself the treat, so you can remain dedicated and stay true to your Calorie Prescription!

Dr. Sue