The Grapefruit (Hollywood) Diet?

Today, we are going to discuss the grapefruit diet, which is a rehash of the hollywood diet from the 1930s. So, I have brought along my own little starlight to help determine if claim is fact or fiction.

The claim is that if you eat the grapefruit diet, then you will lose weight. There are three proposed mechanisms.

1. Meal-Replacement

The original diet was something like half a grapefruit, a boiled egg and melba toast, as a meal replacement. So, you ate that for all of your meals. That would put you somewhere between 500-800 calories pre day, which is really low. It would produce weight loss. It's so low, it fits in the range used by medically-supervised, clincial weight loss settings.

Before you try that, I highly recommend that you talk to your doctor or your regisitered dietitian about it.

2. Pre-Meal (Preload)

The second mechanism is using grapefruit as a pre-meal, or what we now know as a 'preload'. The idea is that you would eat half a grapefruit before your meals. It would put something in your belly and provide some calories, so you would eat less at the meal.

I have seen this same claim for drinks, shakes, bars, supplements and fiber products using the idea of a preload. But, this has actually been put to the test. Eighty-five adults classified as 'obese,' (BMI = 30.0-39.9) were randomly assigned to (127 g) grapefruit, grapefruit juice, or water preload for 12 weeks after completing a 2-week caloric restriction phase. The findings indicate that “incorporating consumption of a low energy dense dietary preload in a caloric restricted diet is a highly effective weight loss strategy. But, the form of the preload did not have differential effects on energy balance, weight loss or body composition.”¹

In other words, it did not matter what the preload was, but the preload did help consume less calories (i.e., caloric restriction), thus weight loss happened. There was nothing magical about the grapefruit, unlike mechanism #3.

3. Magical Ingredient

There is supposedly a magical ingredient in grapefruit, such as a fat-burning enzyme, that helps with weight loss. To my knowledge and research, this magical enzyme has not been found. The 18-day Hollywood diet was reportedly derived William H. Hay’s work (1866-1940), who supposedly mentioned that grapefruit contained a special fat-burning enzyme. I found nothing of the sort. It was likely a twisting of his suggestions of digestive enzymes from the pancreas with proper food combining.

So, I will call this mechanism, 'busted'.

References

1. Silver, H. J., Dietrich, M. S., & Niswender, K. D. (2011). Effects of grapefruit, grapefruit juice and water preloads on energy balance, weight loss, body composition, and cardiometabolic risk in free-living obese adults. Nutrition & metabolism, 8(1), 8.