One claim is that eating a big breakfast will lead to weight loss. It can be confusing for laypeople because almost anything can begin with 'clinical tests show' and sound authoritative.
Research did suggest that eating a big breakfast reduced total calorie intake over the day but it only looked at the ratio of breakfast calories to daily calories and in a new Nutrition Journal study Dr. Volker Schusdziarra from the Else-Kröner-Fresenius Center of Nutritional Medicine says this ratio seems to be most affected by people eating less during the day. In other words their breakfast was proportionally, but not absolutely, bigger.
Schusdziarra conducted a study in which over 300 people were asked to keep a journal of what they usually ate. Within the group sometimes people ate a big breakfast, sometimes small, and sometimes skipped it all together.
Schusdziarra said that "the results of the study showed that people ate the same at lunch and dinner, regardless of what they had for breakfast", meaning that a big breakfast (on average 400 calories greater than a small breakfast) resulted in a total increase in calories eaten over the day of about 400 calories. The only difference seen was the skipping of a mid-morning snack when someone ate a really big breakfast, however this was not enough to offset the extra calories they had already eaten.
So it seems that there is no magic and that, unfortunately, in the fight for weight-loss, eating a large breakfast must be counteracted by eating substantially less during the rest of the day.
Restrict calorie intake. It's guaranteed to work.