The phrase "flake out" means to lose energy or fail to follow through on commitments. The opposite of flake out could be dependable or reliable - someone who can be counted on to complete tasks or stay true to their word. Another antonym could be energized, vibrant, or dynamic - a person who is high-energy, focused and consistently productive. In contrast, someone who flake out could be described as lethargic, indolent or unproductive. Overall, the antonyms for flake out highlight the importance of dependability, focus and energy in achieving our personal and professional goals.