Yo-Yo Dieting

Diet studies are interesting to read and have fascinating data to look at. The first thing that strikes you is how many of the study participants quit partway through the study – typically 50-80%! (See the topic ‘Staying Motivated’) The second thing that you notice is that weight loss occurs early on but nearly all of it is regained within 3 years – the end time point of most research studies. There are some follow-up studies and longer-term studies that show that by year five all of the weight has been regained plus a little extra. For those who are constantly trying diet after diet (Yo-Yo dieters) the long-term effects are a steady increase in overall body fat.

The reason behind this can be seen in the included graphs. In graph #1 we see that a typical diet (whether or not exercise is included) includes a dietary calorie restriction – the black line. Almost every diet has some kind of this unsustainable starvation included. Many people can maintain this restriction for two or three weeks, maybe a month, but we always see a huge decrease in diet adherence over the following months until calorie intake returns to where it was before the diet. Graph #2 shows what body weight (in blue) and fat mass (in green) during this same time (all of these graphs are based on data from the same original study). The change is body weight is greater than the change in fat mass meaning there is a significant loss of muscle – we will come back to this in a minute.

Now lets overlay these two graphs to make graph #3. This graph shows several things. First, fat was being lost (green line) while energy intake (black line) was less than energy intake (dark blue line) – no surprise there. Second, body weight was already starting to increase as energy intake approached energy expenditure – this is liver glycogen stores returning to normal levels as well as some protein retention by the body. Third, while energy intake (black line) returned to pre-diet levels by the 9^th month, it is taking energy expenditure (dark blue line) a lot longer to return to pre-diet levels. It will eventually sometime between year four and five, but until then ~96% of the extra energy intake is being converted to fat and stored away. By the time we get to year five body weight is higher than when we started to diet - we have more fat and still less muscle than when the diet was started (assuming little or only aerobic exercise). Well, that didn’t go as planned now did it?

So, it looks like the culprit is the calorie intake returning to pre-diet, normal levels but the energy expenditure lagging behind for a couple of years. Calorie intake returns to normal quickly as part of normal appetite function. The energy expenditure is lower as a result of the loss of the metabolically active muscle lost during the starvation portion of the diet when calorie intake levels were decreased so much (see the topic “Maintaining Muscle Mass”). Anyway, the end result is long-term fat mass gain. For someone who goes through several dieting cycles you can envision the long-term results.

So what can be done? Can diets work? (See the topics “Do Diets Work?” and “How Much Can I Lose, Which Diet is Best For Me?”)

Successful weight loss can be visualized  in graph #4. Fat and weight loss are maintained. When you look at the long-term change required to maintain that loss it comes to ~200 kcal/day lower energy intake than before as shown in graph #5. Lasting lifestyle change is key for this to work, whether dropping 200 kcal/day of something(s) from our diet or increasing physical activity 200 kcal/day or some combination (see “Weight Loss Lifestyles” topic). Change is possible and we are here to help you to plan it, see it, and be it!

Our dietCompare Calculator can show you what calorie level can best minimize muscle loss. 

Check it out at: www.myfuturefigure.com/dietCompare_Calculator.html

How much weight can I lose? Which diet is best for me?

The obvious answer to the question of “Which diet is best for me?” is the diet you will stick to and follow. There are a lot of things that play a role in this including lifestyle preferences, motivation and type of diet. Also, it is possible to lose weight rapidly, several pounds a weeks, but the more important question really is: How fast can I lose fat while maintaining muscle mass?

Goal: we want to maintain lean body mass while we lose fat. To do this we want to:

• 1) Not decrease calories so far that the body burns muscle for energy
• 2) Optimize macronutrient content of diet to maximize fat metabolism
• 3) Weight-bearing exercise to maintain muscle mass

There has been a lot of discussion about whether a high-carb, low-calorie or a low-carb, low-calorie diet is more effective for weight loss. Even the US Congress has called in experts to testify concerning this question. Now anyone can evaluate the effects of different diets on fat and muscle loss by using the dietCompare Calculator available from MyFutureFigure. (www.myfuturefigure.com)

The body is a very dynamic system that utilizes carbs, fat and protein as energy sources at different levels depending on our energy demands and supply - our energy balance. The extent to which we utilize each of these for energy also depends on the status and stores of each at any given energy balance level. The equations that the dietCompare Calculator utilizes are based on published scientific research studies. These studies investigated the individual contributions of carbs, fat and protein to total energy utilization during periods of underfeeding (like when you go on a diet), overfeeding (like when you eat too much and gain weight) and at energy balance (when your calorie intake from food matches your body’s energy expenditure and your weight is stable).

Using the dietCompare Calculator will do several things for you. First, it provides you a reliable prediction of your future body weight (up to six months in the future). The equations and mathematical descriptions of energy utilization this calculator is based on were validated against six separate published scientific research studies and was found to give predicted results within 10% of actual reported values - predictions were within 3 pounds for individuals losing 30 pounds. These equations are based on groups of sedentary (non-exercising) people and individual factors like how well you stick to your diet, individual metabolic rate, and lifestyle and exercise might cause your results to be different from those predicted. For example, if you exercise you could lose weight faster than predicted by this calculator.

Second, the dietCompare Calculator lets you see how calorie level effects weight loss. You can experiment with different calorie levels to find out how much you will need to reduce calorie intake to reach your weight loss goal.

Third, the dietCompare Calculator lets you compare the composition of weight you will lose on a diet based on the composition of that diet - how much fat, carb, and protein typically are in that style of diet. Just like weight training exercises will decrease muscle loss during a diet, a diet higher in protein will also lower muscle loss typically seen during a diet, thereby maximizing fat loss. We are not advocating one diet over another, simply letting you know what to expect based on how the body works. Try the dietCompare Calculator for yourself and step into the future of weightloss.

Robert T. Davidson, Ph.D.

Do Diets Work?

Statistics show that 95% of all diets fail, but does that mean that diets do not work? Can a person lose weight without dieting? What exactly does it mean to diet?

Our bodies are incredibly complex, dynamic systems that require energy to function. We consume energy in the form of food and utilize energy even when resting and sleeping. There is no time that we do not utilize energy, though the highest energy utilization is during very active or prolonged physical activity. When we consume more energy than we utilize our body will store the excess energy either in the carbohydrate storage form of glycogen in the liver or as fat distributed throughout the body with the end result of increasing body weight . Simply, this is known as the energy balance principle. When we utilize more energy than we consume the energy stores are mobilized from the glycogen stored in the liver, from the fat stored throughout the body and from protein in throughout the body (particularly our muscles) to make up the difference and body weight will go down. (The composition of our diet has a large effect on the composition of mobilized energy during a period of negative energy balance - see the article “Diet Composition”)

Our lifestyle and personal habits essentially determine our energy balance state, whether we are consuming more or less energy than we are utilizing, or if it is balanced. The body, by genetic design, tries to keep us in balance through appetite and hunger control (the article “Fat Genes?” and “Hunger and Appetite” discuss what has gone wrong in those who may be missing these natural feelings due to genetic faults or errors). Over time, usually before we leave childhood, we can learn to disregard natural feelings of satiety and develop habits of overindulgence that result in a lifestyle that leads to long-term weight gain. Eating is also a very social activity. Many of our holidays and social gatherings involve eating and feasting which often leads to an overindulgence of energy, and when coupled with ignoring natural satiety feelings the next few days leads to a natural weight gain. Seasonal and occupational effects on lifestyle occur as well. During winter months, many people limit outdoor activities due to colder temperatures and shorter periods of daylight while many occupations also limit physical activity and energy utilization as well.

A diet may be considered a drastic, short-term change in lifestyle. Short-term because by definition it is unsustainable - stay on it too long and you may die depending on how drastically you have decreased energy intake (the article “Eating Disorders” describes a condition where people do end up starving themselves to death while maintaining a mental image of being overweight). A diet is drastic because of the effects it has on the body and mental psyche. A diet can be used to decrease body weight dramatically. There are generally two problems associated with unsuccessful dieting. First, the diet is so drastic that the change in lifestyle required is untenable to the participant for the time period necessary to lose the weight. The participant will cheat and consume more energy than the diet called for and fail or simply outright quit. The second problem is faced by people who achieve a meaningful weight loss and then return to the lifestyle that caused weight accumulation to begin with. The end result of which is returning to the pre-diet weight or even heavier (more information in the “Yo-Yo Dieting” and “Weight Loss Lifestyles” articles). It is very important that when making the leap from contemplating going on a diet to actually implementing one that proper planning has taken place to determine a reasonable weight change and time period for the weight change to occur. It is also important to make sure the diet plan design has support and feedback designed into it to increase dietary compliance and have ample support. There are several good commercial weight loss plans that include varying levels of support and motivation helps. 

There is a website called the National Weight Control Registry that reports the weight loss efforts of individuals who have lost significant amounts of weight and maintained that weight loss (http://www.nwcr.ws/).  It is of interest to note that 45% of those listed on this web site lost weight on their own while 55% lost weight with the help of some diet program. Also, 98% report modifying food (energy) intake while 94% report increasing physical activity with walking being the most prevalent activity chosen.

While it may be true that 95% of all diets fail it is also true that dieting can work if the person can maintain motivation to stick to their diet and a lasting lifestyle change occurs (see “Changing Lifestyle” and “Staying Motivated” articles). 

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Welcome!

I'd like to welcome you to this blog. We will post select files from our Advice and Answers page here and would appreciate your feedback and ideas for future posts either in the comments or via email to: info@myfuturefigure.com



Thanks.

Robert