A question on plateaus

alzaman5925

I've been active on MFP for around 3 1/2 weeks now, and I've been losing weight pretty steadily so far during these early days. I am curious to know though, as it seems like just about everybody has experienced a plateau at least once during their weight loss journey, how many weeks in or after how many lost pounds did you find that your weight became stagnant on the scales? What sort of things did you have to do to start losing again?

I suspect that answers will probably vary a lot, but I'm trying my hardest to keep my metabolism from slowing down by remaining active during my low calorie intake, and so it would sort of be interesting to find out how long it might take to reach a plateau at which point I'll have to change up my routine slightly. I'm trying to lose weight quite aggressively right now, but the calories will be slowly added back into my diet so that I can tone up and not find myself worrying so much about what the scales are saying.

Thanks in advance!

alzaman5925

Bump

caraiselite

i would consider a plateau one month of the scale not changing if you still have more than 20 pounds to lose.

kaervaak

Two main factors contribute to plateaus:
Metabolic adaption and muscle catabolism

Metabolic adaption occurs whenever you eat a calorie deficit for a prolonged period of time. Your body decreases your metabolism because it sees this as a famine or some other kind of hardship and it doesn't know how long it will last. To fight this it starts rationing. The general advice for getting over this kind of plateau is to eat at maintenance for 2 weeks to reset your metabolism. This probably won't fully reset you, but it will get your body to stop being so stingy with the fat oxidation for a little while. As your body fat gets lower, this process happens faster and so you'll need to do resets more often. At very low body fat percentages, there is a technique known as "refeeding" that basically involves doing a metabolic reset once or twice a week (one or two days of eating at maintenance) to try to stave off metabolic adaptation as much as possible.

Muscle catabolism is kind of the dark side of weight loss. Your body uses both muscle and fat for energy in a calorie deficit and it turns out that muscle is actually more bioavailable than fat. So if your body is really stressed and taxed for energy, it will preferentially break down muscle tissue for energy. As your body breaks down more and more muscle (and you won't replace that muscle while in a caloric deficit), your metabolism decreases. The best way to prevent this kind of plateau is to eat a high protein diet and do whole body resistance training. This basically tells your body that you need that muscle and it shouldn't break it down unless it really really has to. Also, you shouldn't run a huge caloric deficit, eat a very low calorie diet or engage in extreme cardio training while in a caloric deficit (these are all very stressful on your body and encourage catabolism) if you want to preserve your lean body mass and subsequently, your metabolism.

alzaman5925

Thanks guys for your replies!

I'm pretty new to this, kaervaak, so it's good to read a lot of the information I've garnered from stalking the forums in one comprehensive text. Thanks for taking the time to post your findings so eloquently. I have a few questions about some of your explanations on the role metabolism in the body. Please excuse my lack of knowledge where it becomes evident!

I'm still really confused by this whole fat vs. muscle conundrum. From a layman's perspective, I don't understand why the body would want to burn through muscle before burning through fat. I was under the impression that fat exists as an energy store to be used during an energy deficit. I've also read that it's actually quite hard to burn through muscle, and that it's a misconception amongst dieters that it becomes the primary source for fuel during exercise.

I've only read a couple of articles, but they seem to say that fat and carbohydrates work together in a fairly equal ratio as sources of energy during resting periods. During workouts, carbohydrates predominantly get used up at around 85% and the remaining 15% sees fats and amino acids taken up. (I suppose that could actually be incentive to work out later on in the day when you have a carb store, rather than early in the morning!)

I've copied and pasted this quote from the article I've found, and if true, it really contradicts what a lot of people have been saying on MFP:

"A 1999 study done at West Virginia University and published in the "Journal of the American College of Nutrition" showed that people who go through light resistance training regularly, even if they eat a minimal amount of calories per day, will still retain all of their muscle mass."

http://www.livestrong.com/article/202524-does-running-burn-fat-or-muscle/

The other thing that baffles me a lot is that running, as an example of a cardio workout, does require muscle strength in order to execute movement. It uses all of the lower body muscles and very lightly the upper arm muscles, in conjunction with strengthening the heart muscle. I know these sorts of workouts are listed as 'cardio' exercises, but we use our own body weight to act as a form of strength resistance on our limbs during this sort of training, something that would surely encourage muscle growth at best in those areas, or at least encourage muscular maintenance.

The other thing which has sort of been hanging around at the back of my mind for a little while is the idea that eating less will eventually, after a few weeks, cause a decrease in the rate of one's metabolism. Certainly, considering dieting on it's own, I think that's a logical idea because of the body's adaptive responses, like a form of metabolic homoeostasis. However, if you're generally keeping yourself active, whether occupationally, domestically, or by setting aside time to aerobically exercise in the day, you actively force the body to increase its rate of metabolism by increasing your heart rate during intermittent periods. Even with light activity, I've been thinking that surely this would offset the metabolic consequences of a lower calorie diet? In this way, I believe that recreational exercise and activity establishes quite an elegant system which helps you to remain healthy and in shape.

I would be honoured if you're able to leave me with your thoughts once again!

kaervaak

Great reply! Its always nice to talk to people who've done their homework :-)

Your post is quite extensive and required some work to find the answers to your questions, but hopefully I'll get to everything.

On muscle vs fat burning:
A major problem with fat oxidation as a fuel source is that fat is not evenly distributed in the body. People with relatively low body fat percentages store most of their fat in their core to protect and insulate their internal organs. This means that when we exercise, the energy taken from the fat has to travel a relatively long way to reach the muscles that are doing the work. This means that during extended low to moderate intensity exercise, the body first uses glycogen stored in the muscles to do the work, but your body only stores about 1200 calories of total glycogen. When that runs low, your body has to use stored body fat and muscle protein to provide energy for further work. If the energy from the fat has to travel a long way to reach the muscles, it's actually easier for the body to break down the muscle that's doing the work for energy since it's so close.

Here's a study that shows that after 1 hour of exercise, subjects used protein (i.e. muscle) for about 10% of their total energy expenditure.
[url] http://jap.physiology.org/content/48/4/624.short [/url]

I would imagine that as the exercise duration increases, this ratio will also increase, but I've been unable to find a reference for this so far. And since muscle is very hard to replace under calorie restriction, most of that loss will be somewhat permanent.

I've found studies that show ratios of fat - non-fat mass loss during calorie restriction from anywhere from 100% fat loss (high protein diet, resistance training) to 60% fat, 40% non-fat mass (very low calorie diet) with typical numbers being 80-85% of weight loss coming from fat as long as the subjects had sufficient protein intake and did some form of exercise.

As a caveat, I will add that the large amounts of muscle breakdown only occurs in people with relatively low body fat percentages who engage in heavy cardio training or people who are protein and calorie deprived.

On carbs vs. fat use during normal exercise:
The ratio of carb to fat use really depends on the intensity of the workout. At high intensity, carbs are the primary fuel source because they reach the muscles so quickly. As the intensity decreases from maximum, fat oxidation can provide a reasonable supply of energy to the muscles (it's slower and less efficient) so it begins to take a larger role.

Fat oxidation as a function of VO2 max during exercise finds an indirect relationship between exercise intensity and lipolysis. At 25% VO2 max, nearly all of the energy used came from free fatty acids, whereas at 65% VO2 max, there was a pretty even split between FFA, muscle glycogen and muscle triglycerides. Extrapolating on this result would say that at rest, nearly all energy expenditure comes from fat, but that doesn't take into account blood glucose use which seems to stay pretty constant while exercising. It's possible that at rest, FFA use and blood glucose use are about even and muscle glycogen and triglyceride use is nearly zero.
[url] http://www.aleixo.com/biblioteca/obesidade/artigos/Regulation of endogenous fat and carbohydrate metabolism.pdf [/url]

I'm going to steal a plot from Peter Attia's blog, the Eating Academy to give you a general sense of energy expenditure (not including muscle catabolism) during exercise at different intensities.
[url] http://eatingacademy.com/wp-content/uploads/2011/12/RQ-explanation.jpg [/url]


In regard to the livestrong article:
I read the paper they cited and what they found is pretty much in line with what people advise on the forum.
[url] http://www.jacn.org/content/18/2/115.abstract [/url]

1. The starting subjects were all quite overweight (BMIs around 35, body fat% around 45%)
2. The resistance training group did not only lift light weights. They had a pretty decent weight program that is detailed in the paper.
3. Everyone in the study ate the same diet and it was a very small amount of food, but it was 50% protein (about 100 grams of protein per day).
4. The control group (who exercised but did not do resistance training) lost significant amounts of lean body mass (4kg out of 18kg lost, 22%)
5. The resistance group lost very little lean mass (0.6kg out of 14.5kg lost, 4%)
6. The main thing to take away from this post is that VLCD (very low calorie diets) work for obese people. They have enough fat stores to adequately fuel their bodies even during exercise. You can't draw conclusions about non-obese people from this study since the biological and metabolic interactions are much different at lower body fat percentages. However, without resistance training, the subjects still lost significant lean body mass during this diet.

Another important point I'd like to make here is on the different kinds of muscle.
Your muscles are divided up into three main groups: slow twitch, fast fatigue resistant, and fast fatiguable.
Slow twitch muscles have low peak force but high resistance to fatigue and lots of oxidative enzymes. They use mostly fat oxidation for fuel.
Fast fatigue resistant muscles are able to maintain their power output over a large number of contractions. They use both glycogen and fat oxidation.
Fast fatiguable muscles have very high power output but become fatigued after a few contractions. They are primarily glycogen consuming.

Muscle fibers are tied to neurons, known as motor units (http://en.wikipedia.org/wiki/Motor_unit_recruitment). Each motor unit has some number of muscle fibers that it controls. Motor units are activated in sequence from the smallest unit to the largest. Slow twitch muscles are generally associated with small motor units. They are activated first and if the workload is light, they are the only motor units activated. This is indicative of an endurance activity such as walking (or for well trained people, running a marathon). As the workload increases, more and larger motor units are engaged. For very heavy workloads, the fast fatiguable muscles are fully engaged and they burn through glycogen very quickly. These are the muscles used in sprinting and heavy weight lifting and they aren't engaged until the workload becomes sufficient to merit their inclusion.

So while running is a strength exercise, a well trained runner has no problem repeating the running step many hundreds or thousands of times. This means that their small, slow twitch muscles are all that is needed for them to run. For untrained runners, this may not be the case and they may need larger motor units to activate in order to propel themselves, hence the ability of untrained/overweight runners to preserve muscle mass while losing weight. It really all comes down to intensity and muscle recruitment. Is the exercise the dieter is doing using slow twitch or a variety of muscle types? Also, running has minimal upper body involvement, so even if their legs become fatigued and are able to preserve muscle mass, they may still lose lean mass from their upper body if they don't do resistance training.

I just spent over an hour writing that reply, so I'm going to take a break and get back to you on the metabolic adjustment stuff.