This paper presents an experimental study of energy dissipation caused by fatigue crack growth in titanium alloys Ti Grade 2, Ti-1.1Al-0.9Mn, and Ti-4.6Al-1.77V using an original heat flux measurement technique. It is shown that significant structural changes occur in the material under plastic deformation, leading to internal energy evolution. As is known, a large part of the deformation energy is dissipated as heat. The developed experimental technique allows high-accuracy measurements of the heat flux caused by plastic zone development at the crack tip directly in the fatigue experiment. Simultaneous measurements of the crack length and displacements in the stress concentration zone allow estimating the energy balance of the tested specimens. Analysis of the obtained data confirms that the stored strain energy reflecting the structural state of the material can be used as a fracture criterion. A kinetic equation is derived for predicting the fatigue crack growth rate in the Paris regime by energy dissipation rate on the basis of heat flux data.