5 Reasons You Aren't Losing Weight with Intermittent Fasting

Obesity is one of the most prevalent and tenacious problems facing humanity today. Obesity wreaks havoc on your body's systems, disrupting hormone production, hurting insulin reception, and causing cardiovascular problems, among many other things. It's a distressing trend that shows no sign of slowing despite dozens of different diet programs, weight loss options, and social movements aimed at addressing the issue.

Many people around the world subscribe to intermittent fasting as a weight loss program, and for some of those people, it works very well. For others, it seems entirely ineffective. What's going on, why might intermittent fasting not work for some people, and what other options do you have?

Let's talk about the science of weight loss.

What is Intermittent Fasting and How Does it Work?

The theory behind intermittent fasting is relatively simple. Where many diets focus on controlling what you eat, or how much you eat, intermittent fasting instead focuses on when you're eating whatever it is that you're eating.

The theory behind intermittent fasting comes from an examination of human societal norms over the past decades and centuries, as well as the rates of obesity around the world. Obesity wasn't nearly as prevalent as it is today, even just 30-50 years ago, let alone centuries ago.

What has changed since then? Well, a lot of things, including the use of many different processed ingredients and preservatives, artificial sugars, and more. But, sociologists note, there has also been a significant shift in culture.

In the past, when the sun went down, there often wasn't much left to do for the day. People would work on handicrafts or simple household chores in the early evening, but they soon went to bed, to rest for the following day. Even with the advent of electricity and modern conveniences like radio and television, these services often shut off before midnight, and people, left with little to do, went to bed.

In the last few decades, however, several things have changed. TV and the internet, as well as games and apps, can now provide you with something to do at all hours of the day. A more globally interconnected world means you might have friends around the world to talk to at all hours of the night. There's a lot more going on to keep you awake and alert much later than used to be culturally normal.

When you're up late, you may find yourself flagging and wearing down. Some people take that opportunity to go to bed; others grab a quick snack to refresh themselves.

This is where the origin of intermittent fasting comes in. You're more likely to be snacking outside of the relatively narrow hours humans used to eat, which both increases the amount of time your body is processing and storing new energy rather than expending stored energy, and gives you more time to be taking in more food.

Since the core of virtually all weight loss comes down to the calculation of calories in versus calories out, a broader window for snacking means more calories in and, especially with our more sedentary lives, fewer calories out.

How Does Intermittent Fasting Work Specifically?

On a more specific level, intermittent fasting chooses a set period of each day where you're allowed to eat. There are a variety of specific plans you can choose to follow, such as:

• 12:12, where you are allowed to eat within 12 of the day's 24 hours, such as from 7am to 7pm.
• 8:16, where you are even more restricted to just 8 hours during which you can eat, such as from 9am to 5pm.
• 5:2, where you pick two days per week, such as Monday and Thursday, to maintain a deep caloric restriction, such as no more than 600 calories on those days; the other five days are normal.

There are other variations as well, such as alternate day fasting, a weekly complete 24-hour fast, or the extreme 4:20 Warrior Diet, wherein you're only allowed to eat during four hours of a day.

Various studies have shown that intermittent fasting works, at least in the short term. For example, a randomized controlled trial of 5:2 showed it was effective for weight loss, especially in the first six weeks, but dropped off over the course of a year.

Intermittent fasting works within our understanding of weight loss in two ways. The first is that, by restricting when you can, it cuts out a lot of additional calories you might be eating through casual snacking outside of those main hours. Since you eat your main meals within your allowed eating time, you won't be hungry to keep snacking, and if you're following your restrictions, you won't snack outside of those hours. It functions as a caloric restriction similar to normal caloric restriction, just based on time rather than the amount of food eaten.

The second is that, after a certain amount of time not eating, your body switches from expecting new energy sources coming in from food, and starts to consume energy it has already stored as body fat. This, combined with an improvement to sleep quality, helps reduce body fat and improve overall health.

What Are the Main Reasons Intermittent Fasting Isn't Working?

While many people try out intermittent fasting and see results, others do not. The question then becomes, why does it work for some people and not others? I've narrowed it down to five common reasons why intermittent fasting isn't working for you.

1: Eating More to Compensate

Intermittent fasting relies on implicit caloric restriction, but one of the primary stumbling blocks is that some people will simply condense the amount they would eat into those hours rather than trim off excess calories that would normally have come outside of those hours.

Since weight loss, again, typically goes back to calories in and calories out at its heart, this means that you aren't actually taking in fewer calories, which eliminates the primary benefit of intermittent fasting. This is more of a problem with the less restrictive forms of the plan, whereas the more restrictive and full-day fasting options make it much harder to compensate.

2: Eating Too Late at Night

One of the main reasons that intermittent fasting works is that the extended period during which you aren't eating allows your body to enter ketosis, where it consumes stored body fat for energy. Normally, this happens while you sleep and stops when you eat breakfast in the morning.

Some people sculpt their intermittent fasting schedules to eat a relatively large meal at the end of their eating period so they have as much energy as possible available for their fasting period. While this seems like it makes sense from an energy standpoint, it counteracts the benefit of intermittent fasting and means your body has a harder time entering ketosis.

A review of nighttime eating found that this impact could be mitigated, either by sculpting what you eat (such as focusing on protein-rich beverages only) and by incorporating exercise. A survey of nighttime eating also found that pre-bedtime meals increased the incidence of waking up during the night. Without these mitigating factors, however, the primary benefits of intermittent fasting are left behind.

3: Not Supporting the Weight Loss

Another reason why intermittent fasting may not be working is if you aren't also taking steps to improve your health and weight in other ways as well. Intermittent fasting has a relatively small impact on its own, such that, in some cases, it can seemingly fade into the background of natural weight fluctuations.

The impact of intermittent fasting can be improved through the use of other weight loss tools, such as shifting to a healthier diet rich in whole foods and lean protein (such as the mediterranean diet), and incorporating exercise into your daily routine. Absent these interventions, intermittent fasting alone is less impactful.

4: Diminishing Returns

One of the biggest problems with intermittent fasting is the body's natural adaptability to changes in circumstances. Many studies have observed that intermittent fasting can be quite effective when done properly for the first several months. However, after a year, the beneficial results tend to drop off.

This isn't unique to intermittent fasting. Nearly any health plan, from caloric restriction to weight lifting, can reach a "plateau" where results and progress level off, and it seems ineffective. Your body is simply good at adapting to a "new normal" and will need further encouragement at those points.

5: Unrelated Health Issues

Intermittent fasting is beneficial in helping to control weight and has a demonstrated positive impact on a variety of illnesses, including cholesterol, insulin control, and some of the markers of cardiovascular disease. However, it's less effective at some things, like blood pressure, than a general caloric restriction diet.

There are, unfortunately, a variety of health conditions, illnesses, and diseases that can make intermittent fasting either less effective or actually dangerous.

• Type 1 diabetics. Intermittent fasting is beneficial for those with type 2 diabetes, but type 1 diabetics need stricter blood sugar control and should avoid the hypoglycemia involved in intermittent fasting.
• People with eating disorders. A disordered relationship with food can be exacerbated by the restrictions of intermittent fasting.
• Individuals with immune deficiency illnesses, which can be impacted in a variety of ways by the imbalance in caloric intake.

Intermittent fasting is also not a good idea for pregnant women for obvious reasons.

Are There Risks to Intermittent Fasting?

Despite the hype, relatively few long-term studies have been performed on intermittent fasting, and of those that have been performed, they aren't always the best or most reliable studies. However, there have been a few causes for concern, either in at-risk populations or in general.

For example, one systematic review that looked at 27 studies found no serious adverse events in intermittent fasting populations. However, a narrative review found that participants in some trials experienced reduction in bone density and lean body mass.

One concerning review that looked at over 20,000 people found a whopping 91% higher risk of cardiovascular death in those undergoing intermittent fasting than those who weren't. While this sounds bad, however, it's also just an observational study and only showed a correlation, not necessarily a causative relationship.

Overall, a lot more study is necessary to determine whether or not intermittent fasting is the right way to go, and if there are any serious long-term risks.

What Should You Do to Lose Weight?

Maybe intermittent fasting is right for you, or maybe it's not. It's hard to say, especially from my perspective.

In my view, addressing obesity is a complex problem and can't be solved with any one simple change. With the calories in and calories out view, you generally need to work on more exercise and less eating, regardless of how you do it.

I also highly recommend working on a healthy diet. A proper balance of macronutrients, and an assurance that you're getting all of the right micronutrients, is essential. It matters less which diet you follow, and more just making sure you're getting what your body needs. I eat a very healthy diet, and even I take a MicroVitamin to round out those micronutrients and make sure I'm getting everything I need.

At the end of the day, there is no singular medication, diet, or exercise plan that is perfect for everyone. You will need to work with your healthcare team to determine what is right for you in your unique health circumstances, and work to reach your own goals in the way that is most effective for you.

Sources

1. Overweight & Obesity Statistics – National Institute of Diabetes and Digestive and Kidney Diseases: https://www.niddk.nih.gov/health-information/health-statistics/overweight-obesity
2. A randomized controlled trial of the 5:2 diet: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0258853
3. Association of Eating and Sleeping Intervals With Weight Change Over Time: The Dail24 Cohort: https://www.ahajournals.org/doi/10.1161/JAHA.122.026484
4. The Health Impact of Nighttime Eating: Old and New Perspectives: https://pmc.ncbi.nlm.nih.gov/articles/PMC4425165/
5. Does the Proximity of Meals to Bedtime Influence the Sleep of Young Adults? A Cross-Sectional Survey of University Students: https://pubmed.ncbi.nlm.nih.gov/32295235/
6. Intermittent fasting and health outcomes: an umbrella review of systematic reviews and meta-analyses of randomized controlled trials: https://pubmed.ncbi.nlm.nih.gov/38500840/
7. Intermittent fasting and weight loss: Systematic review: https://pubmed.ncbi.nlm.nih.gov/32060194/
8. Beneficial effects of intermittent fasting: a narrative review: https://pmc.ncbi.nlm.nih.gov/articles/PMC9946909/
9. 8-hour time-restricted eating linked to a 91% higher risk of cardiovascular death: https://newsroom.heart.org/news/8-hour-time-restricted-eating-linked-to-a-91-higher-risk-of-cardiovascular-death