Why Women Shouldn’t Do Intermittent Fasting

1204-sexy-core-1As research unfolds about intermittent fasting (IF), it becomes more and more compelling as a viable dietary plan for weight loss, leaner body composition and perhaps even muscle gain. However, it must be said, some of the research does indeed steer a certain group of people away from it: namely, women.

As we’ve stated before, one of the main reasons we’re interested in intermittent fasting from a fat-loss perspective is because it seems to promote increased insulin sensitivity — the studies we’ve looked at have all shown this trait, and it makes sense even dating back to our research on diabetes prevention. However, it also appears that the insulin sensitivity increase is gender-specific: Yes, males will get the benefit of a more responsive pancreas after periods of fasting, including sleep and fasted exercise. But a 2005 study from Pennington Biomedical Research Center in Baton Rouge shows that while glucose tolerance is unchanged after fasting, women’s tolerance actually decreases — impaired glucose tolerance is a form of hyperglycemia that is a precursor to diabetes — and insulin response is virtually unchanged.

Another bit of research, a 2010 study from the Institute of Food Nutrition and Human Health at Massey University in New Zealand, found that women also got little to no benefit from fasted resistance training, with men clearly displaying an advantage in skeletal muscle gain. (Source)

The theories as to why these changes alter the sexes differently, of course, relate to the relationship between regular food intake and hormone production. On top of quite a few IF responses from women who say that it caused them to have irregular periods, fatigue and stress, still more published works back it up. Tests in lab rats illustrate a picture of intermittent fasting wreaking havoc with females’ reproductive, sexual and hormonal systems:

In female rats: Any degree of nutritional stress (fasting or mere caloric restriction) causes increased wakefulness (during the day, when they normally sleep), better cognition (for finding food), hyper alertness, and more energy. In short, female rats become better at finding and acquiring food when they fast, as if their bodies aren’t as well-equipped to deal with the stress of going without food. They also become less fertile, while the males actually become hornier and more fertile (probably to account for the females’ plummeting fertility). Ovary size drops (bad for fertility), adrenal gland size increases (which in rats indicates exposure to chronic stress), and menstrual cycles begin to dysregulate in proportion to the degree of caloric restriction. (Source)

In light of the research and information available pertaining to intermittent fasting and its effects on female mammals, we can’t endorse IF as a sensible means for dietary planning for women. While the research looks promising for men, and many have reported great results from intermittent fasting, it appears women need to have a more steady dietary pattern, not only to achieve fitness results, but to maintain a healthy hormonal balance.

The Hormonal Benefits of Intermittent Fasting

IFEarlier, we introduced the concept of intermittent fasting, a dietary pattern that is gaining popularity because of its potential to aid fat loss. By limiting a day’s calories to a 4-to-8-hour span and fasting the rest of the day (for many, this works out to skipping breakfast and dessert), it is possible to influence insulin values and sensitivity within the body, as well as help deplete glucose and glycogen, meaning body fat stores are targeted for energy.

However, research suggests that even muscle-builders stand to benefit from intermittent fasting, and it’s all because fasted states tend to produce more growth hormone — and the studies have shown this for quite a long time.

A Washington University study done in the 1960s asserts what we still know today as a gospel truth: You secrete more growth hormone (GH) while you sleep. Further, the study shows that going to bed in a fasted state — your body really favors burning fat here, especially when there is a shortage of blood sugar or glycogen stored in the muscles — further primes the metabolism for anabolic activity (again, all going back to the pancreas and insulin).

Now, add in resistance training to this mix, and you’re creating a perfect storm of sorts: The fasted state you stay in until right after your training session increases the production of GH. The fasted sleep you got the night before this has done it even more. And the protein-and-carb-heavy meal you consume immediately after training pretty much throws the whole muscle-building, fat-burning process into motion by signaling to the pancreas to release anabolic insulin, which carries glycogen to your muscles for immediate recovery — and, because of your previously fasted state, there isn’t left-over blood sugar waiting to be used or burned, so your body doesn’t need to store it as fat.

A 2003 Sports Medicine study explains the benefits of exercise on growth hormone production:

Resistance training results in a significant EIGR (Exercise-Induced GRowth hormone). Evidence suggests that load and frequency are determining factors in the regulation of hGH (human growth hormone) secretion. Despite the significant EIGR induced by resistance training, much of the stimulus for protein synthesis has been attributed to insulin-like growth factor-1 with modest contributions from the hGH-GH receptor interaction on the cell membrane. (Source)

In short, you’re bolstering your GH production four ways: Sleep, fasting, exercise and timed eating. And the hunger that you might first experience when adopting intermittent fasting subsides, fast — remember, we’re a species that spent centuries not knowing from where or when our next meal was coming from. We were hungry a lot. Our bodies produce a substance called Ghrelin that basically decides when we feel hungry, for how long, and what to do with metabolic energy. And, as you might’ve guessed from our theme here, it plays a role in signaling the release of growth hormone when we do eat. Its name is cutely derived: (Growth Hormone Release-Inducing = Ghrelin)

Once your body knows (yes, your body learns, and very quickly) that you’re not going to be eating every three hours, and that a fasting period is coming, hunger side effects like crankiness and morning irritability from skipping breakfast will fade. Ghrelin will make sure of that.

The bottom line on intermittent fasting, as far as hormones go, is that research strongly indicates it can provide a significantly anabolic, fat-burning environment based on the body’s hormonal responses to the changes it would go through. And who doesn’t want that?

Intermittent Fasting: Is It For You?

Most of what we know to be good dietary practice revolves around a few tenets that we’ve hammered home: Eat six small meals a day; eat protein with every meal; do not let yourself go into “starvation mode,” etc. One dietary trend that is gaining traction, however, throws all of these to the wind — and people are getting results with it.

It’s intermittent fasting, the most popular form of which is a “feast and fast” mode that gives you a specific time period in which you can eat, followed by another in which you don’t. There are three major components to intermittent fasting that, when we consider their role in fitness and dietary nutrition, become very interesting: insulin sensitivity, hormone production and energy storage. This article is meant to focus on the role of insulin sensitivity and the possible benefits of intermittent fasting.

Intermittent fasting: It's good enough for Wolverine. Is it good enough for you?

Intermittent fasting: It’s good enough for Wolverine. Is it good enough for you?

Anyone with a famous body do it? Yep.

What we know about how the pancreas reacts in different stages can clue us in to why intermittent fasting very well could be a viable dietary strategy. Everything we’ve come to know about the role of insulin, not only in fat loss but in muscle gain and even in diabetes, suggests that we probably don’t need to be providing blood sugar to our bodies every three hours; true enough, most people following a nutritious diet tend to stay away from the frequent carbohydrates that are eventually turned into glucose anyway. But, large calorie spikes, carb or not, can indeed cause jolts of insulin to help move and transport all those nutrients — the question is, how do we 1) take advantage of insulin, which is a natural anabolic hormone, and 2), keep our bodies sensitive to it so that we get those advantages more frequently?

Intermittent fasting — in our context, eating only in a four-to-eight-hour window immediately following exercise and eating no other calories outside of it — helps promote insulin sensitivity. When your organs and tissues are already saturated with stored glucose, ready to be used as energy at a moment’s notice, and you eat a meal, the pancreas still secretes insulin. When insulin saturates the body, though, it remains in the bloodstream, and your body becomes more and more resistant to its effects — continuing down this road of constant insulin presence in the blood leads to diabetes. Those who exercise frequently use this stored glucose as fuel, which means that when they eat, the insulin has a place to go, a role to play, instead of settling in the bloodstream. That concept is one of the main ones behind intermittent fasting: by diminishing the frequent supply of glucose in the body, you can encourage your body to instead turn to stored body fat for energy and at the same time keep it sensitive to insulin.

The Journal of Applied Physiology took a good look at this very topic, and the basic premise of its findings: the body responds to insulin the most after a period of fasting. Your blood sugar levels deplete as you sleep, and do so even more as you fast (and, as we’ll explain later this week, do so even more as you train). This can set you up for massive anabolic boosts if you choose healthy foods and time your feast periods properly (i.e., right after your workouts), and also add another major benefit: body fat loss.

Diabetes Awareness and Prevention at NUTRISHOP

Both living with and preventing diabetes is an important part of the human diet today. The common associations with high blood sugar, increased body fat and/or obesity and hypertension make diabetes a real, dangerous and prevalent disease, especially in Western cultures, where the “standard” diet guidelines have gone by the wayside.

To battle this, it’s recommended highly that everyone — not only athletes, dieters or fitness models — control their dietary sugar intake. This one step alone is a major victory in preventing and addressing diabetes.

So, while we love the aesthetic benefits of lowering dietary sugar — namely, reduced body fat and a leaner frame — there are big-time health benefits to it as well. The purpose of this week’s blog is to show how dietary changes can make a big difference in your everyday life.

To begin with, we want to explain why protein is needed with each meal to balance blood sugar. The digestion process normally works this way: The body absorbs the sugars from food and converts them to glycogen (blood sugar); then, the pancreas releases the hormone insulin to help carry glycogen as fuel to the muscles and other cells for function. Diabetics’ bodies either don’t respond to the insulin enough, or the pancreas doesn’t make enough (or both).

Over time, too many high-glycemic foods (sugars) blunt the body’s sensitivity to insulin, and that sugar gets stored in the blood and as fat cells. This, fortunately, can be countered with some wise eating habits.

Glycemic weight can be lowered in meals by a higher protein content. Because glucose helps to shuttle protein to the muscles, it is less likely to be stored as fat, and over time, this adds up. The body will not be so used to sugar spikes that it is desensitized to insulin — the very culprit behind diabetes. This is why our advice is to eat some protein with every meal. Keeping your sugar intake low, while balancing it with protein, is a great way to manage blood sugar and body fat.

That is why our meal plans (always FREE with purchase) that help you lose fat are designed to balance blood sugar as well — because that is the best way to burn body fat. We customize these for everyone, and we can tailor your plan to include the healthiest possible plan for you.

Stay tuned throughout the week for the top NUTRISHOP products that are either diabetic-friendly, or that will be safe, low-sugar options.


One of the best steps you can take in fighting high blood sugar is to make sure you get enough quality protein without adding tons of sugars. For example, most “side dishes” tend to add lots of simple carbohydrates — people eat steak, but they need mashed potatoes; they have chicken, but they need white rice; they have lean ham, but need a sweet roll with it. Being diligent about making sure your clean protein sources don’t get bogged down with high-glycemic foods is important.

But what if you have a sweet tooth? This is where a tasty protein shake can work wonders. NUTRISHOP carries several brands of whey protein powder blends that taste great and have just one gram of sugar, including FORZA PRO and PRO7EIN SYNTHESIS. And remember, a high protein intake often leads to a faster metabolism, which in turn helps to process the occasional simple sugars that much more efficiently. This is how blood sugar and pressure is kept low — regulating the body’s insulin production by controlling simple sugar consumption and encouraging a faster metabolism.


One of the top ways you can avoid or deal with blood sugar problems is to cut out simple sugars from your diet, or at the very least limit them. But for those of us with a sweet tooth, the options when it comes to facing a bland diet or just caving in and eating sugar aren’t all that appealing.

Even natural sweeteners — honey, nectar, etc. — don’t help us. They still contain sugars that have the same insulin-spiking glycemic effect and they still carry big calorie totals. That’s not our goal.

That’s where artificial sweeteners come in, but over the years, they’ve taken somewhat of a hit in their reputation and developed a bad rap. NUTRISHOP is all for all-natural products when they promote health, but there are some things in nature that just don’t help our bodies look good or function well. Natural sugar is just one of those things, and when science can step up and provide a healthy alternative, it’s worth listening.

A recent investigation from the Mayo Clinic broke down the different types of artificial sweeteners and found that the reputation they’ve earned are hardly justified, while some “natural” products don’t deserve the hype they get. Below is a look at the most common artificial sweetener, sucralose.

  • Sucralose: Definitely the safest and most common artificial sweetener, you might see it most of the time when you’re fixing up your coffee at Starbucks or in a restaurant. The classic pink-yellow-blue sweetener packets are all actually different types of sweeteners (the yellow one, Splenda, is sucralose). Many of the exclusive NUTRISHOP products contain this favored sweetener, approved by the FDA in the ‘70s as a completely safe alternative to sugar. Sucralose is actually derived from sugar itself, its 600 times sweeter than sugar and is virtually calorie-free.