Two big meals 'better' than six snacks for diabetics

Behind the Headlines

Friday May 16 2014

Diet can have a significant impact on the symptoms of diabetes

Healthy breakfast choices include porridge, fruit and eggs

“Only eating breakfast and lunch may be more effective at managing type 2 diabetes than eating smaller, more regular meals,” BBC News reports.

The report focuses on a small study which found that when people with type 2 diabetes ate two meals a day they lost more weight and had lower blood sugar levels at the end of 12 weeks than when they ate six smaller meals a day.

The study involved 54 overweight and obese people with type 2 diabetes who followed the two diet regimens, one after the other, over the course of 12 weeks.

Both diets were designed to provide the same amount of calories – 500kcal less than each individual needed in a day.

The study was relatively small and short term, and in a very select group of people with type 2 diabetes who were willing to make considerable changes to their lifestyle. It’s also important to note that people in the study continued to take their usual diabetes medications during the study.

Results need confirmation in larger and longer-term studies in broader groups of people with type 2 diabetes. Whether the results apply to people without diabetes (as some reporting suggested) is also not clear.

If you do have poorly controlled diabetes you should not make radical changes to your eating habits without first consulting with the doctor in charge of your care.

 

Where did the story come from?

The study was carried out by researchers from Charles University in Prague and other research centres in Prague and Italy. It was funded by the Ministry of Health of the Czech Republic and the Agency of Charles University.

The study was published in the peer-reviewed medical journal Diabetologia which has been made available as an open access, free of charge PDF (233kb).

The Mail Online suggests the results may apply to anyone, rather than just those with type 2 diabetes, which is unproven.

The Mail’s photo of a massive breakfast including pancakes slathered in butter and syrup and use of the term “big platefuls” may mislead people into thinking that they can eat anything for breakfast and lunch and still lose weight. This is not the case. Both diets in this study were calorie restricted and provided 500kcal (roughly equivalent to a “Big Mac” hamburger) less than the individual needed in a day.

Consuming more calories than you burn off during the day, in any pattern, is likely to result in weight gain.

 

What kind of research was this?

This was a crossover randomised controlled trial comparing the effect of having two versus six meals a day in people with type 2 diabetes.

Diet is an important part of controlling type 2 diabetes.

The researchers report that some observational studies, but not all, have suggested that more frequent eating may increase energy intake and risk of overweight or obesity. Another study suggested that eating one larger meal may be better than two smaller meals for controlling blood sugar levels in people with diabetes.

However, the effect of meal frequency in people with type 2 diabetes has not been tested in a randomised controlled trial (RCT).

An RCT is the best way to compare the effects of different interventions (in this case different meal patterns). This is because randomly allocating people into groups is the best way of ensuring that the groups are similar in their characteristics. This means that any differences seen in their outcome are due to the interventions received.

In a crossover RCT, both groups received both interventions, but in a different order.

 

What did the research involve?

The researchers compared a six meal regimen with a two meal regimen in 54 people with type 2 diabetes over 12 weeks. They looked at changes in body weight, liver fat content, insulin resistance, and pancreatic cell function when the participants were eating in the different patterns.

All people in the trial were receiving oral medications for their diabetes, and all were overweight or obese.

The nutrient composition and calorie intake for both meal patterns were planned by the researchers.

They both provided 500kcal per day less than the person’s energy expenditure requirements.

The researchers gave tutorials to the participants over four days on how to compose and prepare their diets, and they also followed up with them during the study.

Half of the participants were provided with their meals by the researchers, and the other half prepared them themselves.

The two meal pattern included breakfast and lunch, and the six meal pattern included three main meals (breakfast, lunch, dinner), and three smaller snacks. Participants were randomly allocated to which pattern they tried first.

After 12 weeks of one pattern, they switched to the other pattern.

The participants were asked not to change their normal physical activity patterns during the study. Their medications were also not changed unless medically necessary.

The participants completed a three day dietary food record at the start of the study and at the end of each 12 weeks on the dietary pattern. Their physical activity levels (using a pedometer and questionnaires) and outcomes such as blood glucose, insulin tolerance, and weight were also assessed at these time points.

 

What were the basic results?

Based on their diet diaries, there was no significant difference in calorie intake with the different patterns, or in physical activity (steps per month).

The researchers found that people lost weight with both meal patterns. They lost significantly more weight when they were on the two meal pattern (3.7 kg lost on average) than with the six meal pattern (2.3 kg lost on average). The two meal pattern was associated with better fasting blood glucose levels.

 

How did the researchers interpret the results?

The researchers concluded that for people with type 2 diabetes on a reduced calorie diet, consuming these calories in two larger meals (breakfast and lunch) may be more beneficial than eating six smaller meals during the day. They say that new treatment strategies should consider meal frequency, as well as calorie and nutrient composition. However, they do sound a note of caution that further studies are crucial before making recommendations on what meal frequency is best.

 

Conclusion

This study suggests that different meal frequencies can have an impact on body weight in overweight and obese people with type 2 diabetes. The RCT design used increases our confidence that these effects could truly be down to the meal patterns rather than other factors, but there are some limitations:

  • The study was relatively small and short term, and in a select group of people with type 2 diabetes who were willing to make considerable changes to their lifestyle. Results need confirmation in larger and longer-term studies in broader groups of people with the condition.
  • The researchers only assessed meal intake based on diet diaries at the end of each diet period. They acknowledge that they cannot rule out that the participants did differ in their calorie intake when they ate in the different dietary patterns.
  • Physical activity was assessed as a step count using a pedometer and questionnaires, but this may not have fully captured the participants’ physical activity levels.
  • The diets were highly planned, and provided to some participants. The results may be better than what might be achieved with less supervision and meal provision.

Researchers are not certain why eating the same amount of calories, but in different patterns through the day, might have differing effects. They made various suggestions, including differing effects on resting energy expenditure or on the nervous system and hormones affecting hunger, or an impact on our bodies’ daily rhythms.

This is a complex area and is likely to be studied in further research.

The news has suggested that eating two meals a day may also be beneficial for controlling weight in people without diabetes.

It is not possible to say for certain whether this is the case until there are trials in this group of people.

However, it is important to note that both dietary patterns tested were calorie-restricted, and both resulted in weight loss.

Even if you just consume breakfast and lunch, if you consume more calories in it than you burn off during the day this is likely to result in weight gain and not loss.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Analysis by Bazian

Edited by NHS Choices

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