Published January 2, 2019
By Tim Newman
Fact checked by Jasmin Collier
Sticking to a strict diet can be challenging, so our eating patterns can fluctuate wildly. A new study looks at how these changes might impact cardiovascular health.
How does eating well intermittently affect our heart?
As we roll into 2019, many people will be trying out new diet regimes.
For many of us, sticking to a nut-filled, burger-free, fish-heavy Mediterranean-style diet will only last a matter of days before we return to the realms of cheesecake and cheese boards. Though eating right over the long-term reduces the risk of cardiovascular problems, we know much less about how a fluctuating dietary regime impacts our heart health. Because so many people choose a diet and then gradually stray from it, researchers are interested in how yo-yo dieting might influence markers of cardiovascular disease. A team led by Prof. Wayne Campbell, of Purdue University in West Lafayette, IN, set out to investigate. The scientists recently published their findings in the journal Nutrients.
Altering eating patterns periodically
To investigate, the scientists inspected data from two previous studies into dietary interventions carried out by the same group of researchers at Purdue University. The participants of these studies followed one of two eating patterns: a Mediterranean diet or a Dietary Approaches to Stop Hypertension (DASH) diet. Lead study author Lauren O'Connor explains these two eating patterns, saying, "Our DASH-style eating pattern focused on controlling sodium intake, while our Mediterranean-style focused on increasing healthy fats. Both eating patterns were rich in fruits, vegetables, and whole grains."
Participants followed their eating pattern for 5 or 6 weeks. After this period, the scientists assessed their cardiovascular risk by measuring a range of parameters. These included blood pressure and levels of fats, glucose, and insulin in the blood. Following the 5–6 weeks of dieting, participants went back to their standard eating patterns for a further 4 weeks. Then, after another cardiovascular assessment, they were restarted on DASH or Mediterranean diet plans for an additional 5–6 weeks. Finally, they had one more checkup at the end of this period.
A cardiometabolic 'rollercoaster'
The analysis showed that, as expected, the cardiovascular markers improved when the individual stuck to the diet. Then, once they had returned to a less healthful eating regime, the biomarkers became less favorable again. Then, once the healthful diets were restarted, the metabolic markers once again improved. The key message is that only a few weeks of healthful eating can make measurable improvements to markers of cardiovascular health, but at the same time, it does not take long before they return to their unhealthy state once a person terminates their healthful diet.
"These findings should encourage people to try again if they fail at their first attempt to adopt a healthy eating pattern," Prof. Campbell says. "It seems that your body isn't going to become resistant to the health-promoting effects of this diet pattern just because you tried it and weren't successful the first time." More research will be needed to explore whether yo-yo dieting has an impact on long-term health.
Some studies have shown that losing and gaining weight again in a cycle, or weight cycling, could cause stress to the cardiovascular system. However, the evidence is certainly not overwhelming, and some scientists question whether weight cycling has any adverse effects at all.
Overall, the results are bittersweet; they show that just a few weeks of dietary change can produce measurable improvements in health markers. On the flip side, after just a few weeks following the abandonment of a new diet, those benefits are lost.
However, if a person restarts their healthful eating plan, the benefits can be won back in the same short amount of time.
As such, Prof. Campbell's message is one of stubborn persistence: