According to a quick google search. Itchy skin is accompanied by weight loss and visa versa so I guess we can take comfort in the fact it's working and have a good scratch!
See below for what to do from livestrong.com
If you've lost weight and are annoyed by itchy skin, you are not alone. If your weight loss was intentional, the solution may be as simple as adjusting your nutrient intake. If your weight loss was not, the combination could indicate a health condition. Always consult a health care provider for proper diagnosis if you have itchy skin that accompanies weight loss.
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If you are following a weight-loss plan, make sure you are getting enough iron. Iron deficiency can cause a mild, generalized itching. In this condition, your body doesn't have enough healthy red blood cells, which bring oxygen to your body's tissues. Iron supplements may help, but some people don't tolerate these well. You need to check with a doctor before trying one, advises Medline Plus. Foods that contain iron include meats, whole-grain bread, raisins, eggs, legumes and fish. A vitamin B2 deficiency also can cause itchy skin. Vitamin B2 also is called riboflavin. It's found in eggs, dark green veggies and whole and enriched grain products, according to "100 Questions and Answers About Sports Nutrition and Exercise," by Lilah Al-Masri and Simon Bartlett.