April 17, 2013
Breakfast skipping compared to high protein breakfast: effect of appetite control in girls.

Are you a girl who regularly skips breakfast? Read on because this well-controlled study is for you.

Introduction:  Breakfast skipping is strongly associated with a greater chance of weight gain.  Furthermore, this trend is also linked to poorer food choices.  Higher protein meals are becoming more popular as a way to improve satiety and appetite control. The purpose of this study was to examine if it is better to skip breakfast or eat one higher in protein in regards to appetite control throughout the remainder of the day.

Methods:  Twenty overweight or obese girls between the age of 15-20 who normally skip breakfast were recruited for this study.  They were tracked for 7 consecutive days and randomized to one of 3 groups: breakfast skipping (BS), a normal cereal meal for breakfast (NP), or a high-protein breakfast (HP) consisting of beef and eggs for breakfast.  Breakfast and lunch were controlled but the rest of the day they were free to eat as much as they wanted. 

Results:  

  • NP & HP led to a 60% reduction in daily hunger.
  • HP lead to a greater increase in total fullness.
  • NP & HP led to a 30% reduction in daily desire to eat.
  • HP breakfast but not the others suppressed an important hunger stimulating hormone (ghrelin) by 20%.
  • HP breakfast but not the others increased an important satiety-stimulating hormone (PYY) by 250%.
  • BS & NP led to greater evening snacking than HP.

Discussion/Conclusion:  A small breakfast of merely 350kcal led to reductions in perceived hunger, the desire to eat, and prospective food consumption.  In addition, it also increased fullness.  What is even more interesting is that the high-protein breakfast group had additional benefits of a reduction in the hunger-stimulating hormone ghrelin, increases in PYY (a hormone that makes you feel fuller), and decreases in evening snacking, particularly of high-fat foods.  The authors note that a limitation of this study was that the breakfast skipping group and the high-protein group had similar total amounts of calories consumed during the day.  Although this study looked at 1-week of food consumption, it is not certain if eating a high-protein meal for longer periods of time (a year or more) would prevent weight gain.  

My input:  The most obvious inferences that the authors draw come from the simple fact that the breakfast skipping group is fasted.  Of course, their perceived hunger/fulness, desire to eat, and prospective food consumption will be higher in the morning because they just woke up.  I think the most powerful part of the study came from the blood draws and the actual measurable physiological significance that a high-protein breakfast did decrease a hormone responsible for making you want to eat and increase a hormone that tells your brain that you are full.That is what truly stands out as powerful rather than all the other results based solely on questionnaires.  For that reason, I’d suggest trying out the high-protein diet over your standard cereal-based breakfast and seeing how it works with your own feelings of satiety throughout the day.

Leidy et al Am J Clin Nutr. 2013 Apr;97(4):677-88

November 28, 2012
Nighttime snacking reduces whole body fat oxidation and increases LDL cholesterol in healthy young women.

This one is for the night-eaters. The ones who find themselves diving into some snacks before bed.  You know who you are.  Did you know they actually consider this a syndrome though?

Introduction:  Night eating syndrome is classified as a delay in the circadian timing for food intake which can alter metabolism and eventually lead to obesity.  This syndrome is diagnosed as ingesting a quarter of your total energy for the day after an evening meal up to three times per week.  The aim of this study was to see how two weeks of snacking either during the day or at night, without changing meal frequency, would alter energy metabolism in lean young women.

Methods:  13 lean healthy women were recruited with 7 of them being randomly assigned to the snacking during the day group (10:00am) and the other 6 to the snacking at night group (11:00pm).  After the two weeks, their energy expenditure and substrate utilization were measured in a whole-room respiratory chamber for one day.  The snack consisted of merely 200kcal.  Breakfast, lunch, and dinner were given at 9:00am, 2:00pm, and 7:00pm for each group during the two weeks.

Results:

During the afternoon, the group that snacked at night had a significantly higher RQ (using more carbohydrates instead of lipids for energy) and significantly lower fat oxidation.  There was a small decrease in 24-hour fat oxidation with the group that snacked at night but this was not statistically significant.  LDL cholesterol levels significantly increased as well in the group that snacked at night.

My input:  A major strength of this study was the strict control of meal frequency during the two weeks.  However, the groups were small and likely underpowered when it came to statistical significance, particularly with the slight decrease in 24-hour fat oxidation which could have been significant had they recruited more volunteers.  Regardless, this study shows the importance of nutrient timing and how eating at specific hours of the day can alter our metabolism due to the hormones naturally controlled by circadian rhythms at those hours.  It is a necessity for the nutritional science field to step away from calories in versus calories out and start looking more towards nutrient timing at different hours of the day under different conditions (rest versus pre/post-exercise).

Hibi et al Am J Physiol Regul Integr Comp Physiol. 2012 Nov 21

April 5, 2011
Three Square Meals a Day Paired With Lean Protein Help People Feel Full During Weight Loss

Eating fewer, regular-sized meals with higher amounts of lean protein can make one feel more full than eating smaller, more frequent meals, according to new research from Purdue University.

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