Food Quality vs Food Quantity: Why Both Matter for Optimal Health

When it comes to nutrition, it’s common to hear arguments about whether food quality or food quantity is more important for health. Some people believe it’s all about calories, energy balance, and portion control. Others argue that nutrient-dense, whole foods are the key to long-term wellness regardless of calorie count. The truth is that both quality and quantity play crucial roles, and neither should be ignored.

In the health industry there will always be polarising figures that fixate on one path to health. Often ignoring equally compelling evidence for another view, to sustain their own righteousness. All this does is create confusion whilst simultaneously lining their own pockets. The key is to find balance between the polarity. Somewhere in the middle lies the un-sexiest answer to optimal health. Let’s talk about why BOTH matter. 

Food Quality: The Foundation of Long-Term Health

Food quality refers to the nutrient density and composition of the foods you eat, including vitamins, minerals, fibre, antioxidants, and phytonutrients, as well as how processed the food is. Diets high in ultra-processed foods tend to be energy-dense but nutrient-poor, contributing to inflammation, metabolic dysfunction, and chronic disease risk. Does that mean avoid them like the plague? Absolutely not. Like with many other topics, the dosage makes the poison. There is very much a place in the diet for ultra processed foods, but in a ratio of 80/20, with whole foods making up the majority. 

One of the most compelling pieces of evidence for diet quality comes from the Nurses’ Health Study and the Health Professionals Follow-up Study, which tracked over 74,000 adults for 12 years. Researchers found that participants who improved their diet quality, measured by the Healthy Eating Index, Mediterranean Diet Score, and DASH score, reduced their risk of death by 8–17% compared to those whose diet quality declined (Sotos-Prieto et al., New England Journal of Medicine, 2017).

Similarly, the DASH Randomised Feeding Trial demonstrated that shifting toward a diet rich in fruits, vegetables, whole grains, and lean proteins lowered systolic blood pressure by about 5–6 mm Hg, even when body weight and sodium intake were kept constant (Appel et al., New England Journal of Medicine, 1997). This proves that the quality of your food choices can directly influence important health markers, independent of calorie intake.

Key takeaway: Prioritising whole, minimally processed foods improves cardiovascular health and longevity, even if your weight doesn’t change. 

Food Quantity: Energy Balance Still Rules the Equation

While food quality sets the stage, energy balance, the relationship between calories consumed and calories burned, dictates body composition and metabolic outcomes. Chronic over- or under-consumption can lead to hormonal and metabolic disruptions that undermine even the cleanest diet.

The CALERIE Phase 2 Randomised Controlled Trial investigated moderate calorie restriction in healthy, non-obese adults over two years. Participants who reduced intake by approximately 12% experienced significant improvements in blood pressure, insulin sensitivity, cholesterol, and inflammation markers, despite only modest changes in body weight (Ravussin et al., The Lancet Diabetes & Endocrinology, 2019).

On the other hand, studies on overfeeding show the opposite effect. Sustained calorie surpluses increase liver fat, insulin resistance, and harmful lipid species (ceramides), even over short periods (Rosqvist et al., Journal of Clinical Endocrinology & Metabolism, 2019). Energy excess, not just poor food quality, drives much of the metabolic dysfunction seen in obesity and non-alcoholic fatty liver disease.

Key takeaway: Managing calorie intake, avoiding chronic surpluses or extreme deficits, is fundamental for maintaining metabolic and cardiovascular health.

The Bottom Line: It’s Not “Quality vs Quantity” — It’s Both

Focusing exclusively on either side misses the bigger picture. A nutrient-dense diet made up of whole foods is essential for longevity and vitality, but ignoring total energy intake can still lead to fat gain and metabolic issues. Conversely, tracking calories without caring about food quality may help manage weight but can leave you nutrient-deficient and inflamed.

Optimal health lies in the middle ground:

• Prioritise high-quality, minimally processed foods to nourish your body and reduce disease risk.

• Balance total energy intake to maintain a healthy body composition and metabolism.

Or as I like to tell my clients:

“Food quality builds the foundation. Food quantity shapes the structure. You need both for a strong, healthy body.”

References

1. Sotos-Prieto M et al. Changes in Diet Quality and Mortality Among US Adults. N Engl J Med. 2017;377:143–153.

2. Appel LJ et al. A Clinical Trial of the Effects of Dietary Patterns on Blood Pressure (DASH). N Engl J Med. 1997;336:1117–1124.

3. Ravussin E et al. Effects of Two Years of Calorie Restriction on Cardiometabolic Risk Factors (CALERIE Phase 2). Lancet Diabetes Endocrinol. 2019;7:673–683.

Rosqvist F et al. Overfeeding With Saturated Fat Increases Liver Fat and Ceramides. J Clin Endocrinol Metab. 2019;104(12):6201–6213.