Intermittent Fasting vs Volumetrics

Intermittent FastingNo food-type restriction — any foods within the eating window/days; water, black coffee, or plain tea during fasting hours.

VolumetricsVery-low-density: broth-based soups, non-starchy vegetables, most fruit. Low-density: starchy vegetables, whole grains, legumes, low-fat dairy, lean protein — the everyday staples.

Intermittent FastingNone specifically — timing, not food type, is restricted.

VolumetricsNone eliminated — higher-density foods (nuts, seeds, dried fruit, oils and butter, chips, chocolate, cookies) are enjoyed in smaller amounts, not banned.

Intermittent FastingDefines the diet: 16:8 daily time-restricted eating window, 5:2 (two lower-calorie days/week), alternate-day fasting, or Eat-Stop-Eat (one or two full 24-hour fasts/week).

VolumetricsNo specific eating window — organized around food energy density, not timing.

Intermittent FastingWeight loss / metabolic health via changing meal timing rather than food choice.

VolumetricsWeight loss via increased fullness/satiety per calorie.

Intermittent FastingPeople who find a fixed eating window easier to sustain than counting every meal, or who naturally skip breakfast anyway.

VolumetricsPeople who find restriction-based dieting hard to sustain because they end up hungry, and who like understanding the “why” behind a recommendation.

Intermittent FastingNone specified — only timing is restricted, not macro ratios.

VolumetricsNone — organized around energy density (calories per gram), not macro ratios.

Intermittent FastingSome improvements in insulin sensitivity, blood pressure, and cholesterol in certain trials; no advantage shown over plain calorie restriction in several recent RCTs.

VolumetricsNot tied to a specific health condition — a general weight-loss/satiety focus.

Intermittent FastingMixed — weight loss broadly comparable to calorie restriction, but several well-designed recent trials (TREAT; NEJM 2022) found no added benefit over calorie restriction alone.

VolumetricsStrong relative to similarly-styled diets — comes from a specific, decades-long Penn State research program (Dr. Barbara Rolls), with a year-long RCT (97 obese women) showing greater weight loss and lower hunger from the low-density approach.

Intermittent FastingModerate — no food is off-limits, but timing has to be maintained; not recommended without medical supervision for disordered-eating history, pregnancy, type 1 diabetes, or children.

VolumetricsLow — no foods eliminated, just density-tier awareness; requires some ongoing attention to food composition rather than fixed rules.

Intermittent FastingNo special foods required — flexible and affordable, since only timing changes.

VolumetricsBuilt on inexpensive, widely available staples (produce, whole grains, legumes, broth-based soups, lean protein) with no specialty products required, making it one of the more budget-friendly structured approaches.