If discontinuance of shake brings your heart rate to normal, it establishes no suitability of the shake to your body. As an Ayurveda doctor, I am not in favour of such designed and synthetic weight controlling methods. So will other Ayurveda doctors. Even learned allopathy doctors will not prescribe you such illogical food intakes since they know the drawback of such pseudo health tonics. Wt. control can be done naturally by managing negative caloric intake diet, jogging/ walking, exercises, breathing exercises like kapalbhati, meditation, yogic postures. These will control wt. as well as give strength to your mind and body too. On 21 June, World Yoga Day will be organised all over the globe. Try to find slot somewhere. It will be free. Learn 35 minutes techniques and adopt it. See natural ways to reduce wt. Not only see but do it. You always have the option to start taking synthetic formulae to invite side effects and diseases if you do not like Ayurveda and Yoga approach. After all wt. management may not be achieved in one night or fortnight. You should enrisk inviting bad effects only in case of emergency and other serious diseases by taking synthetic medicines and food when life is at stake. Just to control weight, such synthetics should not be adopted. It s an honest opinion. Hope you get me. Have patience and manage your weight the right way.