Noncovalent interactions determine the structure-property relationship of materials. Self-assembly originated from weak noncovalent interactions represent a broad variety of solution-based transformations spanning micellization and crystallization, which, nevertheless, conform to neither colloid, nor solution sciences. Here, we investigate weak self-assembly in water-amphiphile-oil solutions to understand the connection between amphiphile molecular structure and water solubilization in oil. X-ray and neutron scattering, converged with large-scale atomistic molecular dynamics simulations, support that the amphiphiles assemble into liquid worm-like micelles and loose inverted proto-micelles. The inverted proto-micelles are energetically ready to accommodate a higher amount of water. These structures arise from a balance of intermolecular interactions controlled by the amphiphile tail-group structures. Thus, by linking aggregate morphology to molecular structure, this work sheds insights in the molecular design for the control of water solubility and dispersion in oil.