Subjects who completed the study maintained their body weight within 2 kg of their initial weight throughout the 6-mo period. There were no significant effects of meal frequency on heart rate, body temperature, or most of the blood variables measured. However, when consuming 1 meal/d, subjects had a significant increase in hunger; a significant modification of body composition, including reductions in fat mass; significant increases in blood pressure and in total, LDL-, and HDL-cholesterol concentrations; and a significant decrease in concentrations of cortisol.
It's interesting that there was a significant increase inb blood pressure and cholesterol. Also, the decrease in cortisol is also surprising considering that the fasting would make one think that stress levels would be increased.
I agree that much of what we know or thought is wrong. I would really like to see a longer term study, and it would be interesting to see what they consider a significant increase in BP and cholesterol.
Would you be willing to share a sample of your current meal plan or point me to where you may have already done so? One of the challenges I have with one meal a day is consuming sufficient quantities to feel I am getting solid nutrition. I am 6', male, and 250 lbs. Obviously I am squarely in the looking for weight loss camp. Calculators put my TDEE at 2,300 to 2,800 or so. Shooting for even 2,000 is a struggle in one meal as I get overly full. Thoughts?
Here are the authors' caveats regarding blood pressure and cholesterol:
"Although within normal values, both systolic and diastolic blood pressures were higher than baseline during consumption of the 1 meal/d diet. Experimental data for normal-weight men and women on the effects of consumption of 1 meal/d rather than 3 meals/d on blood pressure have not previously been reported. Overweight men and women showed that consumption of 1 meal/d, with caloric restriction, improved blood pressure and heart rate after exercise (22). In animal models, intermittent fasting without caloric restriction has been shown to decrease blood pressure and heart rate (15). The observed increase in blood pressure in our subject population consuming 1 meal/d may be due to a circadian rhythm in blood pressure (23). Diurnal changes may have occurred, because blood pressure measurements were obtained in the late afternoon in the 1 meal/d diet versus early morning in the 3 meals/d."
The bold emphasis is mine. I really think this explains the discrepency and I'm a little disappointed they didn't take blood pressure measurements at both time points for both groups. Honestly, it's a 20 second, noninvasive test. C'mon, scientists...
"Altered circulating lipid concentrations are recognized as risk factors for CVD (28). In the current study, we found both proatherogenic (increases in total and LDL cholesterol) and antiatherogenic (an increase in HDL cholesterol and a decrease in triacylglycerols) changes after consumption of the 1 meal/d diet. These changes appeared to be independent of the controlled diets, because dietary cholesterol and the ratio of fatty acids were held constant. Studies that have attempted to determine the effects of meal frequency on biomarkers of health, such as lipid concentrations, are inconsistent. In one experimental study, healthy men were fed either 3 meals/d or 17 small snacks/d for 2 wk; subjects consuming the 17-snack diet had reductions in total and LDL-cholesterol concentrations, whereas the concentrations did not change in the subjects consuming 3 meals/d (29). Two studies also showed that omitting breakfast has harmful effects on health outcomes related to CVD (30, 31), and another study showed that this omission may reduce risk factors for CVD (32)."
So basically, they seem to indicate that it's tough to pin down a relationship between meal frequency and cholesterol, and although they found a relationship in this study, there are plenty of other studies that found the opposite relationship or no relationship and they don't really know why.
As a matter of fact; carnivorous eats far fewer meals than herbivorous, maybe a couple of times a week, while the vegetable eating crowd eat almost all the time - just take a look to the African savannah and you will understand that I am right! So depending on which of those two “lifestyles” that you think you belong to will give the answer about how to time your meals! Personally I define myself as something in between extremes, as an homo omnivorous, but I never eat any solid food in the AM anymore…
Thanks Paleobird. I've been to his blog, actually read his most recent earlier today. Does he go into what I am asking about? I've read the posts but they go back some time so I may be forgetting if he covered it. If you saw it recently, please point me in the right direction.
I should say, I do currently IF. I go from 7pm to 7pm 2-3 times a week. I do not attempt to get a massive calorie, single meal in on those days. Instead I eat a well proportioned "normal" dinner.
Thanks again for any guidance!
Last edited by PrimalFocus; 05-17-2013 at 04:09 PM. Reason: Typos
Ketone bodies in the blood stream result from an increase in FFA, not the other way around. In fact, ketones are produced by incomplete beta oxidation of fats in hepatocytes. Beta oxidation requires an intermediate metabolite, oxaloacetate, to completely oxidize fats. Oxaloacetate is a product of pyruvate metabolism, which in turn is the end product of glycolysis. So, when you don't have a lot of glucose around, you also don't have a lot of pyruvate, and ditto for oxaloacetate. The end result of this is incomplete oxidation of fats resulting in higher circulating ketone levels.
With that said, you have probably heard that ketogenic diets mimic starvation. That's all fine and well, but what exactly is meant by that? Consider that there are basically four stages of starvation.
Stage 1 is the post prandial stage and lasts about 24 hours. During this stage your body is still heavily reliant upon glucose for energy and this is supplied from hepatic glycogen.
Stage 2 begins when your liver has exhausted its store of glycogen, so about 24 hours into your fast. At this point, metabolism is still fundamentally glycolytic although it is starting to transition towards fat / ketone energy sources. During this transition, gluconeogenesis ramps up significantly to provide energy. This phase lasts about 48 hours.
At about 72 hours into the fast, you enter Stage 3. In this stage, metabolism has adapted to predominantly utilize fats and ketone bodies as the basic energy substrate. Obligate glycolytic tissues still need glucose to be provided via gluconeogenesis, but the bulk of the substrate for that gluconeogenesis is glycerol from oxidized triglycerides. Overall gluconeogenesis rates are lower than during stage 2. Stage 3 is a steady state stage that can pretty much go on as long as you have fat to oxidize.
Once you run out of fat, you enter Stage 4 starvation. At this stage, the only way to provide glucose for the glycolytic tissues is via gluconeogenesis using protein as the substrate, and weight loss is rapid and death shortly follows.
With that as background, ketogenic diets mimic Stage 3. This means that if you fast, you pretty much get to dispense with Stage 1 and 2, and with the increased gluconeogenesis that those entail, since you're practically living in Stage 3 constantly. This is quite an advantage because Stage 2 gluconeogenesis will use some protein as a substrate, so by being in ketosis, you could theoretically maintain more of your lean mass. Not a bad outcome at all. The only complication, if you can call it that, is that you need to follow a ketogenic diet which is not something for everyone.