You’ve probably heard of intermittent fasting. This diet follows an eating pattern where no or few calories are consumed for periods of time that range from 15 to 24 hours. Short-term clinical trials in humans have shown that intermittent fasting can deliver benefits similar to calorie restrictive dieting including weight loss, improved lipid profiles, lower blood pressure and increased insulin sensitivity.
And although it has reached some popularity and success by many people, it’s not necessarily the best diet for women. Why is that? Intermittent fasting has been shown to have an exact opposite effect in some women, causing excess eating, disordered metabolism and hormonal irregularities – missed periods. Keep reading and find out the low down on intermittent fasting and why there is a better diet, aimed at the female metabolism that will burn fat and build muscle while also balancing out hormones.
But First – What is Intermittent Fasting?
An intermittent fasting diet cycles between a period of fasting and non-fasting. Fasting is refraining from food and drink for a period of time. This diet method does not have any complex rules; just abstain from food for a period of about 24 hours, which is considered the maximum amount of time required to result in fat burning. One fasting period every 3 to 5 days allows for about a 15 to 25 percent calorie reduction over a one-week period. The easy concept of this diet has lead to its popularity, but the ease of its use doesn’t mean its right for you – especially if you’re a woman.
The Benefits of Intermittent Fasting
There is much promise for intermittent fasting as a useful diet for not just losing weight, but also for the treatment of metabolic syndrome, cardiovascular disease and even neurodegenerative diseases. The mechanism by which restrictive energy intake accomplishes this however, is still not clear and appears to be the result of numerous factors including metabolic rate, when the fast occurs, the composition of the diet being used and the duration of the diet.
Benefits include a reduction in the inflammatory response, decreases in resting heart rate and blood pressure, increase in lipolysis or fat oxidation, increase in insulin sensitivity, reduction in glycogen production and increase in ketone production. Basically as the body burns through its glycogen or carb storage it then turns to fat and production of ketones for energy; making this diet a nice match for someone who is following a keto diet.
It’s also been shown to have a reduction in glucose, insulin, leptin levels and triglycerides. On the downside, intermittent fasting can also increase cortisol and ghrelin production, resulting in an increase in the hunger response.
Fasting and Cortisol
Although the act of fasting can result in calorie restriction and this can result in weight loss, when used frequently, the stress of calorie restriction can affect a women’s metabolism especially when compared to men.
Research has shown that fasting can negatively impact female hormones, causing irregularities and excess cortisol secretion. When cortisol is high, fat burning hormones and metabolism are slowed down, while hunger cravings increase. During intermittent fasting, instead of using fat as fuel during the fasting periods, your body will keep cortisol levels elevated while it should be tapering down, leading to the undesired effect of storing fat, instead of burning it off.
If you acutely stress the body it produces a brief surge of cortisol leading to increased energy, which can be beneficial, when used infrequently and not chronically. However, one study that reduced calories by 75 to 90% of energy needs on only one or two days per week – the exact amount recommended for an intermittent fasting diet, was shown to cause hormonal imbalances and increased cortisol levels.
How Fasting Impacts Hormonal Balance
Additionally, fasting has been shown to throw off growth hormone pulses, these pulses are critical for hormonal balance. GH release triggers luteinizing hormone (LH) and follicular stimulating hormone (FSH), which in turn trigger estrogen and progesterone release. This release regulates not only reproduction, but also those hormones that regulate hunger and satiety. Why is this important? Estrogen is tightly regulated to appetite regulating peptides – including those that make you feel full or hungry. Thus if estrogen drops, it’s likely that you’ll feel hungry and want to eat more at the end of your fast!
Researchers believe that calorie restriction, even sporadic restriction, causes hormonal dysregulation, and excess cortisol secretion with the body holding onto its fat stores. It’s a “protective response” as the body stores fat for future survival when calories are scarce.
Food Obsession
Another issue that can be trigged by intermittent fasting is an unhealthy obsession with food. Restricting yourself from food for long periods can cause you to want to eat everything in sight if you are not careful when you break a fast. It can be easy to overcompensate or reward yourself because of the restriction you put yourself through. Additionally, fasting increases the release of hunger hormones and essentially messes with the balance of the opposing hunger hormones. Trying to control those hormones can be challenging and not necessarily healthy either, as these hormones will also be linked to a myriad of other hormones, that regulate other pathways.
Why is Carb Cycling Better
Instead of starving yourself, it could be better to use a calorie restrictive approach, combined with a carb cycling method. This type of diet uses a balance of carbs, fats and protein. This type of diet will keep hormones in happy balance and help lower the stress response resulting in a favorable environment for fat burning. A carb cycle will help optimize carb intake, by eliminating sugar, and switching to sources of carbs from plenty of green veggies and root veggies that are high in fibre. A carb cycling plan gets your body to adapt to burning off fat faster, while still giving you the nutrients you need to build muscle. Women tend to access carbs less than our male counterparts which means they can function just fine on less, and will get better results too.
Cycling between a low carb and a high carb diet can also avoid plateaus in your diet, and ensure that you keep your metabolic hormones up regulated. Follow a low carb diet for 3 to 4 days to deplete your carb stores and tap into fat. Carbs should be around 25 to 50 g. On day 4, eat a high carb diet, doubling or tripling your carb intake.
If you still are interested to try intermittent fasting, you can combine it with any diet including carb cycling, keto or even paleo!
Until Next Time,
Be Fierce & Rule the World!
Lauren Jacobsen
References:
Di Francesco A, et al. A time to fast. Science. 2018. 362(6416): 770-775.
