Eating Most of Your Meals Before 1pm Lowers Blood Sugar

  • Prediabetes affects millions of adults in the US.
  • A new study indicated that early time-restricted fasting may help reduce blood sugar fluctuations in those with prediabetes and obesity.
  • The findings potentially indicate a future treatment option for those with prediabetes.
  • More research on the impacts of fasting on blood sugar and prediabetes is required.

Researchers say they may have a way to help people with prediabetes avoid slipping into a case of full diabetes.

In the US, 96 million adults — equivalent to over one-third of the population — have prediabetes.

Prediabetes is when an individual has higher than normal blood sugar levels. However, they’re not high enough to be diagnosed as full or “overt” diabetes.

Various approaches can help reduce blood sugar and potentially prevent an individual from developing overt diabetes. These include maintaining a moderate weight and engaging in regular exercise.

New research from NYU Langone Health, presented this week at the Endocrine Society’s annual meeting, highlights another potential tactic.

A small study involving 10 patients with prediabetes and obesity found that early time-restricted feeding (eTRF) positively affected blood sugar.

eTRF is a type of intermittent fasting that involves eating 80% of your daily calorie allowance in the first 6-8 hours of the day, before 1 pm. The remaining calories are consumed via a small meal later on.

Previous research has explored the impact of eTRF on blood sugar. However, Dr. Joanne Bruno, PhD, an endocrinology fellow at NYU Langone Health and lead author of the study, said that one key element remained unclear.

“Given that many individuals lose weight when following [eTRF]it’s been difficult to tease apart whether the metabolic benefits seen are merely due to weight loss, or whether there might be metabolic benefits inherent to this type of feeding strategy,” she told Healthline.

To investigate, the participants were engaged in a 14-day study. During days 1-7, half of the participants followed eTRF, while the other half followed a usual feeding pattern (UFP, whereby 50% of calories were eaten after 4 pm). On day 8, the two groups swapped eating patterns and continued with these until day 14.

To ensure that weight changes didn’t influence the results, participants were provided with food to meet their caloric requirements.

Glucose monitors were used to take blood sugar readings throughout the study, while oral glucose tolerance tests were also conducted at the start, middle and end of the research.

Fasting leads to lower blood glucose

The scientists noted three main results. Perhaps the most important was that, compared to UFP, eTRF led to a decreased mean amplitude of glycemic excursion. But what does this mean?

“The mean amplitude of glycemic excursion (MAGE) is a measure of how much time somebody spends with a higher than desirable glucose level in the course of a day,” explained Dr. William Dixon, co-founder of Signos and a clinical assistant professor at Stanford School of Medicine, who was not involved with the study.

“[This] is a reflection of both how high the glucose rose was and how long it was elevated,” he told Healthline. In this instance, participants following eTRF had lower average rises in their glucose levels.

MAGE can be critical in helping determine someone’s risk of developing overt diabetes.

“Elevated glucose levels over time are indicative of insulin resistance and potential future diabetes (in a person with prediabetes),” Dixon said.

Furthermore, those following eTRF also saw their blood sugar levels spend less time “above range” (aka higher than normal) compared to the UFP group. The time spent “in range” was similar between the two eating approaches.

Bruno said he and his colleagues expected eTRF to reduce blood sugar fluctuations and were “happy to see that our hypothesis was correct.”

One aspect of the findings was less than expected.

“Given the short duration of the study, we were surprised to see such a significant decrease in the time spent in hyperglycemic blood sugar ranges,” Bruno stated.

“The fact that we were able to see these differences with just one week of this dietary regimen is exciting.”

Safety considerations for fasting

This research revealed the positive influence that eTRF may have on blood sugar levels in prediabetics with obesity.

Additionally, previous studies have indicated that intermittent fasting may offer benefits ranging from weight loss and lower inflammation to reduced heart disease risk and improved brain health.

However, it’s important to bear in mind that intermittent fasting can lead to potential side effects.

“There are many instances where eTRF may be unsuitable,” said Dr. Florence Committee, a clinician-scientist with multiple specialties in endocrinology and founder of the Committee Center for Precision Medicine & Health.

For example, “any type of restrictive eating program or fasting could cause dangerously low sugar for some people,” she explained to Healthline.

“Some people drop their glucose rapidly, 2-3 hours after a meal, even a healthy meal, and must eat every 3-4 hours or they get fatigued, jittery, or may even pass out.”

other possible side effects include nausea, headaches, dizziness, and weakness.

Dixon added that eTRF (or any intermittent fasting) is likely unsuitable for those on medications, too.

“I would advise patients with prediabetes to discuss their diet with their physician and/or nutritionist before making significant changes,” said Dr. Jacqueline Lonier, an endocrinologist and assistant professor of medicine at Columbia University Irving Medical Center.

If you’ve already been diagnosed with overt diabetes, it’s even more critical to check in with your physician and care team before switching up eating patterns — especially “as [you] may need concurrent medication adjustments,” Lonier added.

Some health concerns present with signs early on, making them easier to recognize and treat.

Unfortunately, “prediabetes doesn’t always produce symptoms, and you can remain symptom-free for years,” said Dixon.

In the absence of symptoms, you can be aware of various factors that enhance prediabetes risk. These include:

  • Having a parent or sibling with Type 2 diabetes
  • Experiencing overweight or obesity
  • Being over the age of 45
  • Engaging in physical activity less than three times per week
  • Having gestational diabetes
  • Having polycystic ovary syndrome (PCOS)

If you’re concerned you might have prediabetes or are at high risk of the condition, ask your doctor for a diabetes screening blood test.

Diagnostic tests can “assess fasting glucose and insulin, as well as the biomarker Hemoglobin A1c,” the Committee said. “[This is] an average measurement of blood sugar levels over the past 100 days.”

These measurements can then determine whether you have prediabetes.

Dixon revealed that, for those without prediabetes, “normal fasting blood glucose levels are between 70 and 99 mg/dL and less than 140 mg/dL within one to two hours of eating a meal.”

On the other hand, those with prediabetes will have a fasting blood sugar level between 100 mg/dL and 125 mg/dL.

The earlier prediabetes is “caught,” the earlier interventions can begin to help slow or stop its progression.
“Overt Type 2 diabetes can be prevented by enacting lifestyle changes including moderating carbohydrate and caloric intake and increasing physical activity,” said Lonier.

While the recent results were positive, what do they mean for the broader prediabetes treatment picture?

Bruno said the results were significant, as “they provide a straightforward dietary recommendation for regulating blood sugar, and potentially for preventing diabetes, which does not require weight loss, calorie restriction, or carb counting.”

Meanwhile, the Committee was optimistic about the role the results could play in enhancing physicians’ knowledge about the impact of food intake on health.

However, she noted, “It is vital to wisely ascertain whether this [eTRF] strategy works for each individual. It will not be practical or safe for all.”

Remember to always check in with your doctor before changing your diet or eating patterns.

Essentially, the latest findings are a crucial starting point for further investigations.

Although longer-term studies are needed, said Bruno, “we are hopeful that eTRF will prove to be a means for diabetes prevention in individuals with prediabetes and obesity.”

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