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

April 10, 2013
Adipose Tissue Resting Energy Expenditure Higher in Women than Men

Apologies for the period of dormancy.  I’m back and I’m bringing you new articles every Wednesday.  With that said, here we go.

Introduction:  Men and women store fat on different areas of the body.  Women store fat in larger amounts of subcutaneous adipose tissue (the fat under the skin) and men store more visceral fat (the fat around the organs).  In general, women have more body fat than men.  How much adipose tissue contributes to whole body metabolism is not well known; therefore, this was the aim of the study.

Methods:  This was a large cohort coming from hundreds of men and women.  The researchers looked at adipose tissue gene expression as well as expression of genes involved in mitochondrial function.

Results: 

  • For the two sexes, fat mass and fat free mass positively correlated with resting metabolic rate (when one went up, the other went up).  
  • Women have a higher metabolic rate per kilogram adipose tissue than men.
  • Women have a higher expression of genes related to mitochondrial function than men.
  • Women have a higher number of brown adipocytes in subcutaneous adipose tissue than men.

Discussion:  Just to give you an idea of the relative contributions of tissue to basal metabolic rate (BMR), the brain and internal organs account for 70-80% but only make up 5% of the body weight.  Skeletal muscle, which everyone in your gym says influences BMR the most, is 20 times lower than the internal organs.  Skeletal muscle accounts for about 15% of a person’s BMR.  Adipose tissue falls in at around 6% of BMR so we can say it is not that active of a tissue.  

From the lab to the gym: So what’s the main takeaway of this study?  The practical message is from bullet point 4 of the results and particularly a molecule found in those brown adipocytes known as UCP1.  UCP1 is a protein that allows the mitochondria to create heat in the brown adipocytes.  Women have a higher amount of UCP1 in their subcutaneous adipose tissue (the fat you want to lose under your skin).  Therefore, this study suggests that women have a higher capacity to burn calories by converting energy to heat.  Of course the internal organs and muscle are going to contribute the most to your BMR, but the higher metabolic rate of adipose tissue in women gives them an advantage to burn more calories in a resting state than men.

Nookaew et al J Clin Endocrinol Metab. 2013 Feb;98(2):E370-8.

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

March 5, 2012
Early Stage Subcutaneous Adipose Tissue Remodeling

How would you like to be in a study where they fatten you up for 2 months?  Well, this group recruited volunteers just for that and have provided a significant advancement in what is known about adipose tissue structural changes during the first several weeks of weight gain.

Introduction:  The purpose was to examine molecular changes in adipose tissue structure after 2 months of an overfeeding protocol. 

Methods:  Forty-four healthy males were recruited and told to increase their daily caloric consumption to excess of 760 kcal/day.  To accomplish this, they added 100 grams of cheese, 20 grams of butter, and 40 grams of almonds to their usual diet.  Fat biopsies were taken at 2 weeks and again at the end of the 2 months.

Results:  MRI revealed a significant increase in abdominal tissue volume both for subcutaneous and visceral.  No changes in mean adipocyte (fat cell) surface size or number.  There was a significant increase in the density of capillary vessels.  As you would expect, there was an increase in the number of genes related to fatty acid and lipid biosynthesis.  There was also an upregulation in genes involved in formation of the extracellular matrix and angiogenesis (the creation of blood vessels).

Discussion/Conclusion:  Although there was an increase in genes responsible for storing excess fat, there was not yet a significant increase in size or number of fat cells.  Interestingly, there was an upregulation in capillary density and genes involved in creating more blood vessels to supply the adipocytes.  This could also be a reason why the extracellular matrix was remodeled to create space during initial weight gain.

My input:  There were also some other important molecular pathways that were downregulated in this study but for sake of boring you I decided to leave those out.  I think the main important finding in this study is the disovery of genes involved in creating new blood vessels for the fat cells.  It makes sense if you think about it, that an increase in adipose tissue would demand a larger supply of blood.  Therefore, it is necessary to increase the amount of vessels perfusing the cells.  This group did well in not only showing this in gene arrays but also in histological staining from the fat biopsies.   Another article from a different group found similar results in that the adipose tissue of obese and insulin resistant subjects had larger vessels but fewer capillaries when compared to lean subjects.  I would not be surprised to see pharmaceutical studies in the near future aiming at trying to reduce the amount of blood vessels as a way to amerilorate adiposity.  After that, I would not be surprised if that is soon the next gimmick in supplement companies’ “fat burners”/thermogenic products.

Alligier et al  J Clin Endocrinol Metab. 2012 Feb;97(2):E183-92.

February 16, 2012
Where your body deposits fat matters in regards to insulin resistance and future cardiometabolic risk.  Here is a figure from a brand new study published by my doctoral adviser in Obesity.  Getting around the ugly statistical box plots, what it means to you is simply that subcutaneous thigh adipose tissue appears to show a protective effect when it comes to insulin resistance (Dr. Amati uses Rd in this case, which is rate of glucose disposal, as a marker of insulin sensitivity).  The higher you are on the scale, the more sensitive your periphery is to insulin.  The worst marker of insulin sensitivity, and what scientists can deem as the dangerous area to store fat, is the visceral abdominal adipose tissue.  These results are all regardless of age and gender.  
Here we see again the apple vs. the pear story in how one stores fat depots where in this case, the pear seems to win, or at least, be favored.

Where your body deposits fat matters in regards to insulin resistance and future cardiometabolic risk.  Here is a figure from a brand new study published by my doctoral adviser in Obesity.  Getting around the ugly statistical box plots, what it means to you is simply that subcutaneous thigh adipose tissue appears to show a protective effect when it comes to insulin resistance (Dr. Amati uses Rd in this case, which is rate of glucose disposal, as a marker of insulin sensitivity).  The higher you are on the scale, the more sensitive your periphery is to insulin.  The worst marker of insulin sensitivity, and what scientists can deem as the dangerous area to store fat, is the visceral abdominal adipose tissue.  These results are all regardless of age and gender. 

Here we see again the apple vs. the pear story in how one stores fat depots where in this case, the pear seems to win, or at least, be favored.

February 6, 2012
One final important remark while looking at fructose is that it has been shown to increase visceral adiposity whereas glucose has been shown to increase sub-cutaneous adiposity.  I don’t think it is necessarily true that one can lead to more storage than the other in the long-term but so far the data trends toward that direction.
Looking at two studies with markers than can lead to increases in fat stores, the first shows that with 42 studies between the years 1966 and 2006, fructose has no effect on:
 body weight with less than 100 grams ingestion per day
fasting triglyceride with less than 100 grams ingestion per day
post-prandial (after eating) triglycerides with less than 50 grams ingestion per day
The second review with 16 reports between the years 1950-2010 states that fructose does increase plasma triglycerides when given with hyper-energetic (overeating) than iso-energetic diet (balanced).  So we have a mix of conclusions.
From these you think you could get away with 1 can of soda per day.  Maybe that is true but don’t forget the short-term studies I posted that have shown deleterious effects, even as short as three weeks, with ingestion of fructose.  Why risk it if it is something you can live without and is not a necessary molecule to ingest in extra amounts?
Since I didn’t get to post last week on it, the sugar month theme will be finished by the end of this week so make sure to check back soon to see the conclusions.  After that, tons of new articles to post on a variety of topics.

One final important remark while looking at fructose is that it has been shown to increase visceral adiposity whereas glucose has been shown to increase sub-cutaneous adiposity.  I don’t think it is necessarily true that one can lead to more storage than the other in the long-term but so far the data trends toward that direction.

Looking at two studies with markers than can lead to increases in fat stores, the first shows that with 42 studies between the years 1966 and 2006, fructose has no effect on:

  •  body weight with less than 100 grams ingestion per day
  • fasting triglyceride with less than 100 grams ingestion per day
  • post-prandial (after eating) triglycerides with less than 50 grams ingestion per day

The second review with 16 reports between the years 1950-2010 states that fructose does increase plasma triglycerides when given with hyper-energetic (overeating) than iso-energetic diet (balanced).  So we have a mix of conclusions.

From these you think you could get away with 1 can of soda per day.  Maybe that is true but don’t forget the short-term studies I posted that have shown deleterious effects, even as short as three weeks, with ingestion of fructose.  Why risk it if it is something you can live without and is not a necessary molecule to ingest in extra amounts?

Since I didn’t get to post last week on it, the sugar month theme will be finished by the end of this week so make sure to check back soon to see the conclusions.  After that, tons of new articles to post on a variety of topics.

November 17, 2011

shesstillasongtoplay asked: First off: LOVE your blog, And now to my question(s)... What is the best way to optimize my workouts for calorie/fat burning? My usual (slowly becoming a rut) routine is to run a 5k usually around 32 minutes, elliptical for 20, and then weight machines for another 20 minutes. I recently started weights because I was told that it burns calories faster than cardio alone? Also which types of teas have the best effect on the metabolism? Or is that effect completely negligible? Thanks -Sara

Hi Sara,

Thank you for the kind words.  Greatly appreciated.  A lot of people in the exercise industry say that it doesn’t matter if you train with weights or do cardio first in regards to fat loss.  However, I always recommend training with weights first and doing cardio last.  The reason I prescribe this is the fact that due to it’s anaerobic properties, weight training will utilize more muscle glycogen as fuel than low intensity long duration running.  If you use your muscle glycogen first, what is left for energy during cardio?  Fat.  Therefore, the body will become more metabolically flexible with this training protocol and have to rely more on fat, especially if you’ve been endurance trained to some extent for a moderate period of time.

In regards to the tea question.  Obesity Reviews published a nice article on fat burners that I posted a few weeks ago when I addressed the question about caffeine.  Let it be known in all of these studies, it is green tea extract that is ingested (at a moderate dose of approximately 270mg), not solely drinking brewed green tea.  It does show potential to increase fat oxidation at rest but unfortunately these doses were always supplemented with caffeine as well.  These results were acute.  As for chronic ingestion, greet tea extract has shown to decrease RQ at rest, which is a marker of an increase in fat oxidation as opposed to carbohydrates.  It even shows the possibility of helping maintain a certain weight after subjects underwent an exercise intervention.  As for exercise, scientists found that ingesting green tea extract before a single bout increased fat oxidation rates by 17% and this was also found after 3 months of exercise plus supplementation.

So there you have it.  It does indeed show a potential to orient the body into burning fat for energy.  I hope that helps and all the best,

Nick

September 23, 2011
"Starvation mode"

You hear this term used a lot in the fitness realm, but I doubt any self-proclaimed guru or personal trainer can even begin to explain the scientific basis for it.  This post was sparked by a question that I received earlier and I thought I would take the time to display some of the most recent findings when it comes to to this theory.  How recent might you ask (which really means is Nick going to link us to more journal articles?).  My answer is as recent as of today (and no).  This time I’ll do all the writing for you, so for those of you who can’t stand doing any reading on your own, I urge you to please take the time to read the below paragraphs so you can learn for yourself what starvation mode is and how to get around it.

Today I attended an obesity conference with some big time names in the field of thermogenesis and body composition.  When I say big time, I mean big time.  Lewis Landsberg came up to my poster and asked me a question (this guy worked in the lab of a gentlemen who received a Nobel prize).  Anyways, I’ll be posting more from this conference within the next few days but now I shall highlight for you now some of the recent ideas when it comes to “starvation mode”.  Okay I promise you can read the one below now for the science.

Starvation mode is actually referred to in the scientific community as “Catch-up Fat Phenotype”.  Maybe this doesn’t sound as smooth as starvation mode but the main driving theory behind this is the classic hunter-gatherer lifestyle.  That is to say, our ancestors from thousands of years ago were primed to go through pro-longed periods of not having food; thus, retaining fat stores to provide energy.  The first basis of this came from a study published in 1950 known as the Minnesota Experiment by Keys et al which found that when individuals are suppressed of food for a period of 12 weeks, once refed, the body would “catch up” or at least try catch up to the weight they had before.  During the period of starvation, their non-specific thermogenesis would decrease and then increase back to normal upon refeeding.  This led scientists, specifically Abdul Dulloo, to investigate the role of adipose tissue in this Catch-up Fat Phenotype.  What he states is that thermogenesis is suppressed by adipose tissue because fat has a desire to save energy, hence the relationship with the hunter-gatherer lifestyle.  Adipose tissue does so by decreasing thermogenesis, which subsequently will reduce calories being utilized in the body and eventually, metabolism as you know it.  Now your next question might be, well what is the exact physiological mechanism for how “starvation mode” works?  During periods of starvation or low-calorie deficits for those dieting for weight loss purposes, skeletal muscle net utilization of glucose decreases which in turn decreases thermogenesis even more due to muscles high metabolic rate in the body.  In addition, the glucose that is not being used by the muscle is then sent to fat, which utilizes the glucose to increase adipogenesis (creation) of more fat, hence where the catch-up fat comes from.  Starvation processes lead to the eventual resistance of drivers of thermogenesis through this mechanism.

To conclude, you must refeed yourself to get out of starvation mode and continue your weight loss endeavors.  Adipose tissue is stubborn and has the ability to program itself to conserve energy from the fat depots that remain.  Give yourself calories to lose more weight? It sounds crazy, but based off of these findings it is the correct way to restore your metabolism back to normal so you can return to a level of burning the remaining fat that you have.  The period that you add back your calories will be long enough to restore your metabolism but not long enough to put fat on again.  Try a period of underfeeding for 6-12 weeks with a refeeding period of 1-2 weeks.  Play around with changing the weeks and see what works best for you.  There is a lot of individual differences when it comes to metabolism, even in twins.

September 21, 2011
New weight loss series.

To the faithful followers,

I get a lot, and I mean a lot, of weight loss questions.  Now when it comes to questions, I do prefer more science based ones but I will answer anything and help you with anything that you desire so don’t be afraid to ask.  Even if you want me to keep it private I will do so.  There are a lot of good science questions that I have been saving to get into details with, but for my followers that want help losing weight and getting into shape I have something special for you for the next four months.

With that said, I am going to soon begin posting about a good friend of mine who gave me permission to use him as “putty in my hands”.  He wants to lose weight and get into shape and he has come to me for advice.  I have not trained anyone since starting my PhD so this is my first one in a long time.  Mostly everyone I train now are older individuals for our study.

This is a good way for all of my followers to see my techniques and see my recommendations for exercise and diet.  Even though this will be specific to my friend, you can still use my methods as a blueprint for your own weight loss endeavors.  Don’t think this means I won’t answer your questions because I will.  I just thought this would be great to add on my blog along with the usual exercise science articles.  Check back soon.  Now all I need is a witty name for the series. Hmmm

Nick