Does Exercise Improve My Weight Loss When Fasting?

When it comes to weight loss, diet is much more influential than exercise. It’s a truth I denied for many years. In my late twenties I became very active and lost weight and fortunately, incorporated exercise, both cardio and weight-bearing, into my daily routine. As often happens, I eventually plateaued, and my weight loss stopped. I always hoped that I could exercise enough to be able to eat whatever I wanted. Turns out the opposite is true: If you eat properly, you can exercise less. I recently discovered intermittent fasting, and after about a year, I think it’s safe to say that this is a way of life for me.

Simply stated, fasting is going without food or flavored beverages for a period of time. Black coffee and water are two of the limited number of beverages that will not “break” your fast. It’s important to note that fasting has many benefits in addition to weight loss. The basic premise is that while in a fasted state, our bodies not only go into “fat burning” mode, but also “cell repair” mode, which causes your body to use stored energy to clean up damaged cells and expel damaged cells and toxins from your body. In addition, fasting can reduce inflammation, improve digestive health, heart health, and brain health, all of which will help prevent disease and contribute to better overrall health as you age. Fasting doesn’t cost anything, requires no equipment, and is easy to incorporate into any lifestyle because you pick when–and how long–you fast. For more information on fasting, check out some of the books by Gin Stephens, Jason Fung, or James Clement.

Exercise is also important for many reasons that don’t include slimming down. Regular exercise can improve your mood and energy, improve sleep, and reduce or eliminate risks for many ailments including high blood pressure, diabetes, depression, arthritis, and some types of cancer. As always, talk to your doctor before beginning a new diet or exercise plan, particularly if you have a chronic health condition like low blood pressure, asthma, or joint pain.

So fasting and exercise can both be very beneficial to your health. The question I’m asking today is, will exercising while fasting improve my success rate when it comes to weight loss?

Working out during your fasting period has been shown to multiply your fat burning efforts. Research shows this number may be as high as a 20 percent increase. When exercising in a fasted state, your body has no choice but to burn calories in stored fat, rather than in food you’ve recently eaten. Insulin is the magic component that causes your body to gain weight. Both fasting, and exercising, can drive that number down. So it makes sense that combining the two will exponentially improve those results. The benefits are present in both cardio exercises and strength training exercises.

In one recent study, all the participants ate junk food every day. Some of the participants exercised after eating breakfast. They still gained weight. Another group exercised during a fasting period and gained no weight, even with the same bad diet. The benefits may be less valuable for certain types of individuals. Other studies have shown that working out during a fasting period may affect performance negatively, and may affect how well your body builds muscle, so fasted exercise may not be best for endurance athletes, or those trying to build larger muscles.

If you’re new to fasting, it is suggested that you get your body used to a fasted state before doing more intense workouts. Build up by starting with walking or cycling. And always drink plenty of water. This is important with both fasting and exercising. The diet you choose during your “eating window,” (the period when you are not fasting), will also affect your results. It’s always good to avoid sugar and simple carbohydrates, focusing more on complex carbohydrates like vegetables, beans, and whole grains. Be sure to get enough protein and healthy fats like avocado, nuts, seeds, and olive oil.

But for most of us who have incorporated either fasting, or exercising into our daily routines, it is likely safe, and in most cases beneficial to weight loss, to incorporate both of these activities at the same time.

Can You Reset Your Body Set Point for Weight?

The simple, yet complicated ways that our bodies work are amazing to me. Simple because we don’t even have to think about most of it: Breathing, heart pumping, blood flowing. And yet, the complication! All those organs doing exactly what they should be doing, exactly when they should be doing it. Multiple systems in our bodies interacting in such complex ways every moment of every day. And although we obviously have learned much about how our bodies work, there is still so much we don’t know.

One area where we’ve made progress but still have much to learn, is in weight management. Clearly this elusive mystery does not have a simple answer, no matter how much we wish it to be so. It’s not just how many calories we consume. It’s not just the types of foods we eat, or how often, or our age, or hormones, or level of physical activity, or genetics. In fact, it is probably all of these things, and several others, that affect our likelihood to maintain, gain, or lose weight.

One idea which has gained popularity lately is the idea of body set point for weight. Simply stated, this theory claims that each of us has a “set” weight where our bodies are comfortable, and our bodies will adjust to keep us at this weight. It makes sense. Our bodies are always fighting for homeostasis, returning us to our “normal” status. If we get an infection, our bodies work hard to fight it off, if we are hot, our bodies produce sweat to cool us off. If we’re gaining weight, our bodies will adjust by putting controls into place to combat this change, perhaps by increasing metabolism. In reverse, if we’re losing weight, our bodies will adjust to make sure we don’t lose too much weight. The evolutionary connection seems clear. Our ancestors, in order to survive, did not want to fluctuate too much in either direction–overweight, or underweight–as this would hinder their ability to function in the more dangerous world. In the case of potential starvation, our bodies would protect us by holding onto fat. So even now, when you cut calories, or reduce your food intake, your body will work to slow your metabolism, and make hormonal adjustments affecting when you feel “full” or “hungry.” In this way, our body actively resists long-term weight loss. It’s not an encouraging theory for those of us who are fighting to permanently lose weight.

Although some studies have backed up the theory of a set point for weight, weight studies are difficult. Scientists can’t control what people are actually doing or eating so results are often self-reported. Also, changes that happen to our bodies can happen over years, even decades, so short term studies are often not effective. While there appears to be some evidence of a set Point for weight, there are some weight phenomenons that cannot be answered by set point such as, Why do college students often gain weight? Why do children who have a lot of screen time more likely to be obese? Why do people who move from Asia to the West often experience a weight gain? Still, there are believers in the Set Point theory, and proponents of the ability to permanently change that predetermined number.

Jason Fung, author of The Obesity Code, has some ideas. Fung’s main claim: Insulin is the body set weight regulator. Insulin causes weight gain. And eating causes insulin production. Some foods cause more insulin production than others, not surprisingly complex carbohydrates and sugars. And just as our bodies can often become resistant to certain continuous exposures, like antibiotics, in the same way, our bodies can become resistant to increased levels of insulin. The development of insulin resistance typically increases insulin production (hyperinsulinemia) so your body can maintain healthy blood sugar levels. Elevated levels of insulin can result in weight gain, which, in turn, makes insulin resistance worse. It becomes a vicious cycle. And diet plays a large part. A diet of highly processed, high-carbohydrate foods and saturated fats has been linked to insulin resistance.

Your body digests highly processed, high-carbohydrate foods very quickly, which causes your blood sugar to spike. This puts extra stress on your pancreas to produce a lot of insulin, which, over time, can lead to insulin resistance. So what are the dietary suggestions for limiting insulin spikes and insulin resistance? Here are Fung’s rules for eating:

  • Reduce added sugars (don’t forget sodas and fruit juices; limit drinks to water, or black coffee or tea
  • No snacking
  • Reduce refined grains (flour and those foods that are mostly flour (bakery and bread) and pasta)
  • Protein: don’t eliminate it and don’t abuse it, 20-30 % of total calories
  • Increase natural fats (olive oil, butter, nuts, full-fat dairy, avocadoes)
  • Increase consumption of fiber and vinegar, which are thought to protect against the insulin stimulating effects of carbohydrates

These all seem fairly obvious. Nothing new. Common sense. So what does Fung think is the missing piece? Something we might not have heard before?

Not just WHAT to eat, but WHEN to eat.

The longer you have insulin resistance (and very likely obesity) the harder it is to reverse it. A diet high in insulin-producing foods can initiate obesity, but over time, the insulin resistance maintains, and exacerbates, the obesity, likely raising our body set point. So how do we fight to lower our body set point? We have to break the insulin resistance cycle by giving our bodies periods of very low–or no–insulin. In this way our bodies never get used to higher levels of insulin, and therefore don’t adjust to create insulin resistance. While we’ve seen that some foods generate more insulin production than others, all foods generate some insulin production. The solution: Fasting.

Fasting tells our bodies that no food is coming, so no insulin needs to be produced. Insulin provides the glucose that fuels our bodies. When glucose isn’t present, Our bodies still need fuel, so it turns to ketones, which is stored fat, for fuel. This state is known as ketosis. With intermittent fasting (periods of fasting followed by periods of eating) our bodies will start to use stored fat, and will greatly reduce the risk of insulin resistance, which leads to obesity. Theoretically, we then can, over prolonged periods of time, potentially reset the weight set point.

So if you’d like to try this weight loss solution, reduce your carbohydrate intake and add in some fasting. Like most sensible plans to lose weight and be healthier, this is not a short-term solution, but one for the long haul. For more information on fasting, check out my blog post ” The Skinny on Intermittent Fasting.” And if you’ve tried intermittent fasting, share your thoughts with us.