Intermittent fasting has become an incredibly popular diet trend in recent years. The 16:8 method, where you fast for 16 hours a day and eat during an 8-hour window, is one of the most common approaches. For many people, 16:8 fasting leads to weight loss, improved health, and other benefits. However, some find that they actually gain weight on this regimen. There are several potential reasons why this may occur.
You’re eating too many calories during your window
At its core, weight gain or loss comes down to calorie math. If you consume more calories than you burn, you will gain weight. Intermittent fasting provides a structure for when you should eat, but it does not necessarily dictate what or how much you should eat in your eating window. If you are consuming an excessive number of calories during your 8-hour window, you may end up taking in more calories over the course of the day than you expend through your basal metabolic rate and activity. This calorie surplus gets stored as fat.
To avoid this, pay close attention to your portion sizes, food choices, and calorie intake during your eating window. Measure portions with cups or a food scale, choose lean proteins and nutrient-rich produce over processed and sugary foods, and aim for a modest calorie deficit each day to promote weight loss. Many find counting calories or macronutrients like protein, carbs, and fat helpful for staying on track.
You’re eating too close to bedtime
With the 16:8 diet, many people choose to eat between the hours of 12pm-8pm. Eating later at night, especially within a few hours of bedtime, can lead to weight gain. Your metabolism slows down when you sleep. If you eat just before bed, your body does not have a chance to burn off those calories before your metabolic rate drops. Those unused calories end up stored as fat. Eating your last meal several hours before bed, stopping eating around 6-7pm, can help avoid this issue.
You’re eating too many meals in your window
While intermittent fasting focuses on when you eat rather than what you eat, eating too many meals in your window can also lead to increased calorie intake and reduced weight loss. Many proponents of 16:8 recommend limiting your meals to two a day – a lighter lunch and a larger dinner, for instance. If you are squeezing in 3 full-sized meals plus snacks into an 8-hour window, you may simply be eating too much food, even if you are choosing healthier options. Try scaling back to one or two meals and focusing on protein, fiber-rich carbs, and healthy fats to increase satiety.
You’re eating the wrong foods
As mentioned previously, food choices matter on intermittent fasting. Even if you are staying in your calorie needs for the day, choosing low-nutrient, highly processed foods that are high in sugar and low in fiber can lead to weight gain. These foods digest quickly, spiking blood sugar and insulin, promoting fat storage, and leaving you hungry again soon after eating. Focus instead on lean proteins like chicken, fish, eggs, nuts, legumes, and Greek yogurt, complex carbs like whole grains, fruits, and vegetables, and healthy fats like avocado and olive oil.
You’re not drinking enough water
Proper hydration is crucial for optimal health and weight maintenance. Many people do not drink enough water day-to-day. Dehydration can slow your metabolism. Drinking more water helps burn calories, suppresses appetite, reduces water retention and bloating, and boosts the efficacy of intermittent fasting. Aim for at least 2-3 liters per day. Herbal tea, black coffee, and other unsweetened beverages can also count toward your total.
You’re eating too much at once when you break your fast
After going 16 hours without food each day on the 16:8 diet, it’s understandable to feel ravenous once your eating window opens. However, overdoing it right out of the gate can lead to weight gain. Eating a huge meal right away can shock your system and actually reduce your metabolic rate. It can also trigger overeating for the rest of your window. Try starting with a lighter meal when you break your fast, then building up to a larger dinner later in the window. Having a small snack first, like nuts or yogurt, can also help manage hunger.
You’re falling victim to “cheat days”
Following a diet plan consistently is crucial for seeing results. But many people find the rigid schedule of intermittent fasting difficult and wind up taking “cheat days” where they eat outside of their window. Even one cheat day can unravel progress when it comes to weight loss. While an occasional slip up won’t completely sabotage your efforts, getting back on track right away is key. Planning ahead, troubleshooting issues that lead to cheating, and being disciplined can help avoid too many cheat days that lead to weight gain.
You’re eating the wrong foods for your body
While the 16:8 diet can be effective for weight loss for many people, everyone’s body and needs are different. Certain foods that fall within general intermittent fasting guidelines may simply not work well for your body and lead to weight gain, while other options click. Pay attention to how you feel after eating certain foods within your window. Track your food intake and watch for patterns regarding what leads to weight gain vs weight loss. Tailor your approach based on what your body responds to best.
You’re not exercising enough
Exercise and activity levels play a major role in weight loss and maintenance. You cannot out-exercise a poor diet – controlling your eating is crucial. But without adequate physical activity, it can be difficult to create a large enough calorie deficit through diet alone. Exercise assists weight loss through burning additional calories as well as building metabolism-boosting muscle. If you are largely sedentary, not moving enough each day can undermine the calorie restriction of intermittent fasting. Try to work in at least 30-60 minutes of exercise like walking, weights, yoga, etc on your fasting days.
You have underlying health issues
In some cases, trouble losing weight or actual weight gain on intermittent fasting could signal an underlying health condition. Issues like hypothyroidism, polycystic ovarian syndrome, depression, and others can disrupt normal hormonal and metabolic function in ways that promote weight gain and make weight loss extremely difficult. Consulting with your doctor and addressing any underlying issues is important if lifestyle measures like intermittent fasting are not producing expected results.
You’re losing fat but gaining muscle
Finally, there is the possibility that the number on the scale is going up even as you are losing fat on the 16:8 diet. This occurs when you build muscle at the same time that you lose fat. Muscle is denser and takes up less space than fat. So while muscle gain is positive, it can sometimes mask fat loss. Pay attention to how your clothing fits, how you look and feel, and your body fat percentage in addition to the number on the scale. Minor weight gain alongside improved body composition is still a success.
Tips for Losing Weight with 16:8 Fasting
Here are some tips to help promote weight loss on the 16:8 intermittent fasting plan:
- Carefully track your calorie intake and aim for a modest daily deficit
- Focus on lean proteins, fruits, vegetables, whole grains, and healthy fats
- Limit processed foods, sugar, refined carbs, and unhealthy fats
- Stay well hydrated by drinking plenty of water throughout the day
- Stop eating 2-3 hours before bedtime each night
- Exercise for 30-60 minutes most days of the week
- Limit meals to 1-2 per day within your eating window
- Weigh and measure portions to avoid overeating
- Address any underlying health or hormonal issues
- Be consistent with fasting and eating windows daily
Sample 16:8 Fasting Schedule
Here is a sample 16:8 intermittent fasting schedule that can facilitate weight loss:
| Time | Activity |
|---|---|
| 7 AM | Wake up and drink water or black coffee |
| 9 AM – 12 PM | Black coffee/tea/water and work hours |
| 12 PM | Break fast with a protein smoothie or yogurt |
| 4 PM | Mid-day snack like nuts or hummus with veggies |
| 6 PM | Moderate dinner with protein, veggies, healthy grains |
| 8 PM | Stop eating for the day. Wind down for bedtime. |
Conclusion
If intermittent fasting is not leading to expected weight loss results, take a closer look at your eating behaviors during your window, activity levels, and other variables. With some troubleshooting and consistency, the 16:8 method can be an incredibly effective approach for weight management for most people. Adjust the style to best fit your needs and pay attention to how your body responds.