20lbs is a lot of weight to lose in just over a month through diet alone. What was your starting weight?
It could be an indication that your sugars are high if you're losing weight rapidly, however, with low carbs it shouldn't be and 7.6 isn't horrendously high. I would recommend seeing your GP and mentioning about the weight loss and perhaps having some further routine blood tests. They should also be able to give you advice about monitoring also but in my opinion it's better to test and be knowledgeable about what makes you high/low. Unfortunately a lot of things can cause weight loss so it's hard to say! If you feel fitter and healthier with the diet changes theres no reason why you shouldn't stop.
Good luck!!