We aimed to test the effects of three different weight maintenance diets on appetite, glucose and fat metabolism following an initial low-energy diet (LED) induced body weight loss. Following an 8-week LED and a 2–3-week refeeding period, 131 subjects were randomized to three diets for 6 months: MUFA, moderate-fat (35–45 energy percentage (E%) fat), high in MUFA with low glycaemic index; LF, low fat (20–30 E% fat) or CTR, control (35 E% fat). A meal test study was performed in a subgroup, before and after the 6-month dietary intervention, with forty-two subjects completing both meal tests. No difference in body weight, energy intake or appetite ratings were observed between diets. Both the LF and MUFA diets compared to CTR diet reduced postprandial glycaemia and insulinaemia and lowered fasting insulin from month 0 to month 6. Following the 8-week LED period lower levels of the appetite regulating peptides, pancreatic polypeptide, peptide YY, glucagon-like peptide-1 and glucagon-like peptide-2, along with increased appetite scores were seen in comparison to measurements performed after the 6-month dietary intervention. In conclusion, the two competing diets, MUFA and LF, were equally good with respect to glucose metabolism, whereas the CTR diet resembling the typical Western diet, high in SFA, sugar and high glycaemic carbohydrates, indicated associations to lowering of insulin sensitivity. Lower levels of appetite regulatory peptides along with increased appetite scores following an 8-week LED and 2–3-week refeeding period, suggest that strategies for physiological appetite control following a LED period are needed, in order to prevent weight regain.