Those who drank water before all three main daily meals reported an average loss of 4.3kg.
Similarly, Missouri University researchers in the United States found obese adolescents invited to tuck in to high-protein breakfasts lost weight over 12 weeks, compared with others who kept getting heavier while eating normally or skipping morning meals.
Of 57 teenagers in the study, those eating 35g of protein from a menu containing milk, eggs, meat and yoghurt lost an average 400g of body fat, while others going without breakfast piled on 1.6kg.
Review editor Dr Jeremy Krebs, a Wellington diabetes expert, described the results as encouraging but very short-term.
"There is evidence that missing breakfast is associated with obesity," he wrote. "There is also evidence that protein may have greater satiating properties than carbohydrate ... However, randomised controlled trials have not been conclusive in demonstrating this."
Dr Krebs said the second study suggested that preloading with water before eating might reduce total daily energy intake by increasing "satiety" and reducing the likelihood of over-indulging.
"A longer trial to demonstrate sustainability is required, but it is a simple, essentially free, easily translated intervention that could be promoted in public health messages."
Auckland City Hospital diabetes specialist Dr Robyn Toomath was wary of both studies - especially after being told the breakfast protein research was sponsored by the United States National Pork Board and the water trial by the European Hydration Institute.
High-protein breakfast food
•Bacon and eggs
• Baked beans on toast
• Milk and yoghurt
