Yes, neoprene belts can harm your skin and cause dark spots. While they do not actually burn belly fat, only causing temporary water loss through sweating, they trap heat, sweat, and moisture against your skin. This constant moisture and friction can cause contact dermatitis, heat rashes, or fungal infections. Over time, this ongoing irritation and friction can lead to post-inflammatory hyperpigmentation, which presents as dark spots or patches. To protect your skin, I advise against using these belts. For safe and effective belly fat reduction, focus instead on a balanced diet and regular exercise.