Cutting Calories by 12% Protects Health, Reduces Weight and Body Fat

Key Takeaways

• Calorie restriction caused a persistent and significant reduction for all measured conventional cardiometabolic risk factors
• Study participants lost an average 1st 2½lbs (16½lbs/7.5kg) by cutting calories by an average of just 11.9%. Most of this loss was fat – 71%
• Significant improvements in factors associated with insulin sensitivity and metabolic syndrome

New data from a two-year Duke Health trial suggests when it comes to cutting your risk for killer ailments such as diabetes and heart disease, there's always room for improvement.

In adults already at a healthy weight or carrying just a few extra pounds, cutting calories significantly improved already good levels of cholesterol, blood pressure, blood sugar and other markers.

The findings of the randomized, controlled trial of 218 adults under age 50 are described in a July 2019 article in the journal The Lancet Diabetes & Endocrinology.

The trial is part of an ongoing project with the National Institutes of Health called CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy).

Results continue to build on the researchers' hypothesis that it's not just weight loss that leads to these improvements, but some more complex metabolic change triggered by eating fewer calories than what's expended.

"There's something about caloric restriction, some mechanism we don't yet understand that results in these improvements," said the study's lead author William E. Kraus, M.D., a cardiologist and distinguished professor of medicine at Duke.

"We have collected blood, muscle and other samples from these participants and will continue to explore what this metabolic signal or magic molecule might be."

The Trial

For the first month of the trial, participants ate three meals a day that would cut one quarter of their daily calories to help train them on the new diet.

They could choose from six different meal plans that accommodated cultural preferences or other needs.

Participants also attended group and individual counselling sessions for the first six months of the trial.

Members of a control group simply continued their usual diet and met with researchers once every six months.

Findings

At 2 years, individuals in the calorie restriction group achieved a mean reduction in calorie intake of 11·9%.

They sustained mean weight reduction of 1st 2½lbs (16½lbs/7.5kg) of which 71% was fat mass loss.

Calorie restriction caused a persistent and significant reduction for all measured conventional cardiometabolic risk factors including change scores for:

• LDL-cholesterol
• Total cholesterol to HDL-cholesterol ratio
• Systolic and diastolic blood pressure

In addition, calorie restriction resulted in a significant improvement at 2 years in:

• C-reactive protein
• Insulin sensitivity index
• Metabolic syndrome score, relative to control

A sensitivity analysis revealed the responses to be robust after controlling for relative weight loss changes.

Interpretation

These findings suggest the potential for a substantial advantage for cardiovascular health of practicing moderate calorie restriction in young and middle-aged healthy individuals, and they offer promise for pronounced long-term population health benefits.

WLR Comment

There is some mystery surrounding the theory ‘calorie restriction leads to longer life’, so it’s good to see the number of good quality studies building up.

We covered a CALERIE 2 Randomized Clinical Trial which found that calorie restriction had positive effects on health-related quality of life recently.

The great thing is, cutting calories by 12% is relatively easy – for many people we’re only talking about dropping 1 chocolate bar or standard bag of crisps per day.

Or even eating 5-10% less of the highest calorie foods we eat – generally high sugar/high fat processed foods.

There’s no need to ban anything!

You can try this and see how easy it would be to cut a few calories, by keeping a food diary for a day or two.

If you do it in WLR, setting your rate of weight loss to ½lb a week gives a calorie restriction of approximately 12%. (Free trial here.)

The problem for many of us when we want to lose weight, is that we want to do it at high speed – which often leads to it being too hard to continue.

For people who are heavier, a 12% calorie reduction on the amount that they need to maintain current weight would lead to a substantially bigger weight loss than 1lb a week.

Reference

2 years of calorie restriction and cardiometabolic risk (CALERIE): exploratory outcomes of a multicentre, phase 2, randomised controlled trial The Lancet Diabetes & Endocrinology