1 hour, 5x a week. Probably not eating enough for that much sugar-burning exercise. You could be bonking from your body not producing enough glucose .
Mark Sisson has some fun breakdowns of the energy needed to support daily exercise. You might want to read up and then compare your food, your body, and where your movement is.
In the quote below, PB stands for his Primal Blueprint program.
On a PB-style low carb diet, with PB-style low training time, the body makes 200 grams of glycogen each day from fats and protein (and then we figure another 100 or so from your veggies and fruits). That gives you enough glycogen to fuel your brain, cruise through an average day and to be able to do a short hard workout – and then do it again the next day. However, when you train long every day (over an hour), your carb needs will increase. The key is discovering EXACTLY how many additional carb grams you need each day to refuel muscles, but also to keep insulin and fat storage to a minimum. Too few and you won’t recover from day-to-day. Too many and you’ll set yourself up for inflammation and unnecessary weight-gain.
Read more: http://www.marksdailyapple.com/prim.../#ixzz3o5CohgVp
A Zumba workout for a female at 200 pounds and 35 years old, would take 800 calories according to a simple calculator found on a Google search.
Since it's moderate-high intensity, say it's 75% sugar-burning and 25% fat burning. That means 600 calories of glucose are needed each day just for the exercise session. That has to be glucose, not coming from your stored fat.
Don't know how much protein, fat, and carb you have, but that might take an extra what, 150 g of protein per day, over and above your usual?
Notice that Sisson assumes you would just add more carbs if carb energy is what you're missing. Personally I would do that too but it wouldn't work if you were zero carb.