So we have all heard of diets that involve fasting to help with weight loss and with intermittent fasting particularly, it should make sense that having less time to eat during the day should mean fewer calories consumed, right? What if I said that continuously fasting from food could actually be detrimental to your health? Over short periods of time such as skipping lunch because you were busy at work that one day (it happens), or maybe you need to fast for religious purposes. That's okay. But if we are purposely fasting in order to lose weight, this is where we may need to take a step back and do some additional research.
What about the studies that support fasting?
If you have researched fasting regimes, it is more likely than not that you have read "positive" (I use quotation marks here because if you read between the lines a bit, they actually aren't amazing results) results on reduced inflammatory markers, loss of weight, reduction in LDL cholesterol (not-so-helpful fats in our blood), triglycerides and total cholesterol, reduced glucose and insulin release and improvements in HDL cholesterol (helpful fats in our blood). But, if you take a closer look at these studies you will find the following:
The majority of studies have been completed on animals
-Um hello, we are human beings, why are we being compared to lab animals that aren't being exposed to as many stimuli and stress as humans do? Animals also don't have the chance to tap out of an experiment when they feel uncomfortable or feel that this lifestyle isn't right for them.
There are many short-term (weeks-months) studies on humans
-What happens to the subjects after a year or two of undergoing fasting? Is it sustainable? Has it impacted their families? Has it made life that much more stressful to have to rely on the clock as to when to eat? What about eating out with friends for dinner? Are you having to count your calories too? Could you have all these additional worries for the rest of your life? Furthermore, if you regularly try diets and have gained and lost weight over the years you may want to rethink taking another diet, or trying to fast as this is what we call "yo-yo dieting". This is the drastic fluctuations of weight over time which wreaks havoc with your metabolism as it doesn't know if it's coming or going from having access to food one day, and not a lot the next. Because of this, our metabolism gives up and stays slow until it knows it will consistently get food. This then leads to putting back on the weight you originally lost, plus more!
The sample sizes of these studies are considerably small
-By sample size I mean the number of participants in the study. Compare this to the number of our population. Do you think the results of thirty people are really representative of you or everyone?
Most human studies do not have a control group to compare too
-The purpose of a control group is to help determine whether the treatment actually worked against similarly treated individuals. This may mean that both groups will be eating the exact same food, and exercising the same amount but one group will be intermittent fasting and the other will not. This determines if the fasting or the other components of the experiment were the reason for the results.
Most participants are females
-If most participants are females, how could we generalise these results to those of males? Additionally, not all females function the same as we all have different amounts of hormones that may affect our metabolism. Some females may be premenopausal, and some post-menopausal. This would affect the rate of weight loss as well as our hunger, digestion and mood,
Other factors are not considered ie. physical activity, family history, education level, amount of sleep, diet type
-In some of the studies, physical activity was not accounted for. How do we know that the biochemical marker adjustments were from fasting alone? How do we know what the participants were eating prior to the study which could affect how high or low their markers went? How much sleep was each person get? Was it more than they did previously due to having less energy or not needing to stay up as late? Did the participants have a family history of cardiovascular disease or diabetes?
Drop out rates
-As most of the studies involving fasting are carried out over a few weeks, the dropout rate may be low. However, if we were to extend this for a year, what would it look like then? Additionally, in a study that was initiated monthly with multiple groups throughout the year, the dropout rate was as high as 20%. This does not mean only 20% drop out of intermittent fasting every year as it was a different group fasting for a month at a time. This means that the dropout rate is potentially higher over a year as some participants weren't lasting a month of this kind of fasting.
No mention of the sustainability of the diets (if people will happily do this forever)
Insufficient data on mood outcomes
-Questionnaires to identify mood changes with intermittent fasting were often completed with small sample sizes or were not completed by the participants. This makes it hard to generalise whether or not mood improves on this diet. Furthermore, other factors may impact moods such as physical activity, life stressors and previous mental health history.
Lack of data on energy and sleep outcomes
-Due to reasons noted above.
Funding is often from an institute or company that supports/ favours weight loss which results in researcher bias
What the research proposes happens to favour fasting
Limiting and changing the times we eat can alter gene expressions that favour improving energy metabolism and weight regulation. Additionally, organisms originally would reduce their activity during the day or night to ensure their physiological processes were performed at optimal times. That is, our body knows when we are resting/asleep and we complete different metabolic functions then, compared to when we are awake. If we were to change this and eat throughout the night (especially for those shift workers) or eat at night (anytime after 6 pm), it is proposed that this physiological process is disrupted as this is when the body is internally ready to "clock off" for the day. Furthermore, it is suggested that this may lead to an interfered energy balance and increased chronic disease risk.
-Okay firstly, many other factors can alter our gene expressions. If you're wondering what this is, essentially some of our genes (the genetics we have from our parents) work as a light switch. Some can be switched on or off depending on factors such as what we eat, physical activity, stress, climate, chemical substances ie smoke and many more. So according to some studies, fasting can affect a gene switch that helps our body to enhance our metabolism. Personally, starving myself does not seem fun when I could eat more healthily and incorporate enjoyable exercise daily.
-When it comes to eating at certain times, this isn't always doable. For instance, if one of your children has an extra-curricular activity at 5:30 pm which is generally when you may have to eat dinner, would you have dinner at 4 pm to give their food time to settle before playing sport? Or would you have to have two separate dinners; you make your dinner earlier and make the rest of your family dinner later? What about work times? I start and finish work at different times every day so there is no way I'd be able to have my dinner at 5 pm when I have a client and I don't finish till 8 pm. And what about those night shift workers? Someone has to work the night shift. Would you change your hours just so you can fast the "right" way? It sounds like more stuffing around to me.
Eating at "suboptimal" times may influence the gut microbiota negatively as during the evening is when our gut starts to slow down which may impact our metabolism and health. Additionally, there has been talk about "ob*se" and "lean" microbiota. The "ob*se" microbiota has been proposed to increase inflammation that is commonly found in individuals in larger bodies.
-First things first, there is very minimal information and evidence on this topic. What we do know is that the gut microbiota is extremely complex and most times. Are there really "lean" and "ob*se" microbiota? No idea, but I do know they should change the name for it. Yes, some individuals in larger bodies may have high inflammatory markers. So can smaller individuals. Whether larger individuals have increased inflammation in comparison to most individuals in smaller bodies, is actually undetermined. Any individuals in any body may have high rates of inflammation due to psychological stress (specifically those in larger bodies as they may face discrimination and bias regularly), depression, anxiety, chronic or underlying disease/ health issue (no, ob*sity is NOT a chronic health condition! I'll save this for another day), certain foods (and no, not all larger individuals eat "rubbish" food, smaller bodied people may also not always have nourishing food either) and physical activity.
Not eating = lower insulin = burning fat. When we eat carbohydrates, these are broken down into glucose. Glucose is the main energy source for our cells. When there is glucose in our blood, the hormone insulin is secreted by the pancreas to allow the glucose to enter our cells. When we have too many carbohydrates that our cells don't use up, it gets deposited into our fat cells for later use. When we go into starvation mode, our insulin levels will reduce as there is no glucose to absorb, and we will derive our energy from the stored glucose in our fat cells. This is how we can reduce weight.
-As someone who works in the eating disorder space, this raises alarm bells and I instantly go into concern mode as this can go too far too quickly. So, what is mentioned above is often included in most studies around fasting. However, this is only a very brief picture of what happens when we don't eat often. As briefly mentioned before, our metabolism actually slows down if we are not eating consistently throughout the day. Yes, it is mentioned that this helps to prevent you from feeling hungry but then we would be overriding our natural hunger and fullness cues. This then may make it difficult to stop fasting after a prolonged period of time because:
We won't know when we are feeling hungry or full. Therefore, we are less likely to eat anything throughout the day as our metabolism is still running low, and this may lead to excessive weight loss (which we really don't want) as this leads to many other health complications.
It promotes disordered eating behaviours if restricting too much. This in turn can lead to developing an eating disorder which then becomes a more serious issue and has detrimental health effects.
Additionally, it is not recommended for anyone on blood pressure, insulin or some other types of medications to fast. It is also not recommended for those who may have electrolyte abnormalities because if we aren't eating, then we aren't getting any electrolytes which could result in something we call refeeding syndrome. As for those with diabetes, if we aren't eating regularly, it makes blood sugar levels rise and fall rapidly throughout the day. We always recommend those with diabetes eat 3 meals and 2-3 snacks daily that are low GI.
Furthermore, if we are fasting for long periods throughout the day, we are more likely to binge eat because we are depriving our body for so long that when it finally has access to food, it goes all out. This is our innate response, as we are not sure (internally) when we may get our next meal so it's now or never. This is a completely normal response if we have ancestral routes from famine or have suffered from inadequate food provision at some time in our life. With this behaviour though, comes the guilt and shame for not following the diet "rules" or because you think you didn't need to eat all that food at once.
In summary, eating regularly is extremely important because:
It regulates your metabolism
It gives you the opportunity to provide you with enough nutrients throughout the day
It keeps your natural hunger and fullness cues in check (you read what your body wants)
It can help in conjunction with certain medications
It maintains your blood sugar levels
Your life is more flexible and free
Less stress around planning food
Eating regularly is something you can do long term
Setting a better example for your children to be happy in their skin and to eat regularly too
More food choices
Gives you a chance to work on other, more sustainable goals
Reduces the risk of disordered eating/ eating disorder behaviours
Still sceptical? Send me a message with your questions!