Dr. Bob Arnot, journalist and health expert, recently published The Coffee Lover’s Diet, a book exploring the relationship between drinking coffee and weight loss. The book argues that coffee is the secret to lasting weight loss due to its ability to increase metabolism, boost energy levels, and curb hunger. He suggests that participants in the diet drink high-phenol, hot, black coffee after every meal, before bathing, and right before exercising.
On the surface, Arnot’s claims sound accurate. Coffee does increase your metabolism, boost your energy levels, and (temporarily) stave off hunger.
But that doesn’t mean you should chug it all day to try to lose weight. Nutritionists, researchers, and health professionals are urging consumers to take a closer look. “If you don’t already drink coffee, I would not encourage you to start in pursuit of weight loss,” nutritionist Kristen Beck told News.com.au.
Not only does the doctor peddle his own brand of high-phenol coffee, creating a potential conflict of interest, but the diet suggested by Arnot’s book is also based on a faulty study and lacks any evidence of weight loss for coffee drinkers.
In the study, Arnot tested two groups of participants: one drinking high-phenol coffee and the other drinking low-phenol decaf. After two weeks of keeping up the habit, participants reported on their mood and energy levels. The coffee drinkers reported better mood and higher energy.
However, there are a few things wrong with his study as evidence for a weight loss diet:
1. It had no direct relation to weight loss.
2. It contained more than one variable (phenol levels and caffeine intake), which is a major research faux pas. As Caffeine Informer explains about the study, “Of course, the people who had the caffeinated coffee were going to report better mood, energy, and productivity since that’s what caffeine does.” Therefore, the study proved nothing about the benefits of high-phenol coffee — and also proved nothing about caffeine.
3. It failed to account for other factors, such as caffeine withdrawal, in the decaffeinated group.
Of course, coffee does have a number of benefits backed up by accepted studies. It has been shown to heighten mood and lower your risk of type 2 diabetes, Alzheimer’s, Parkinson’s, and even cancer.
But that doesn’t mean it will make you lose weight. “Coffee can suppress appetite simply by providing a boost of energy, but relying on coffee as a source of energy … is only short term,” Beck told News.com.au. She compared the use of coffee for fuel instead of food to using a spark plug to start a car. “You still need the petrol to keep you going,” Beck explained.