how much exercise is she getting?
Speaking from experience, the waistline of a beagle can be a challenge even with lots of exercise. I don't generally subscribe to the blanket theory of 10 calories per pound because the nutritional breakdowns in different foods can greatly vary and should be taken into account. However, given the higher protein and fat levels in the grain free formula, you probably indeed do need to feed very little for a beagle who doesn't get much exercise (the fat is not being utilized/thus stored and excess protein turns to fat as well). I usually find the gram of digestable protein per every pound of body weight to be a reliable starting point in gaging feeding amounts. I'm generally not for the more grainy foods, but in this case, if there is a reputable non-diet food with lower protein and fat contents that your beagle can tolerate, it might be a better fit for him at least until the weight is reduced.She does not get much exercise, which with working 10 hour days with a 45 minute commute 4 days a week and getting home at 9 pm, that isn't likely to change, especially now that it is dark when I get home.
200 calories does sound like a little too little. I'll try the 1/3 cup twice a day.