Weight-Loss Researcher: Avoid These Three Foods

Once you embark on a low-carb diet, do you always have to maintain a low-carb diet if you want to keep the kilos off? That’s a question David Ludwig, M.D., Ph.D., answers in his new book, Always Hungry? Conquer Cravings, Retrain Your Fat Cells, and Lose Weight Permanently, which was released in January. Ludwig is a high-profile medical expert who has spent the last several decades publishing weight-loss research articles in major medical journals.

The book emphasises a low-carb, low-glycemic-load approach to healthy eating. It prescribes a three-phase progression, starting with Phase 1 (very low carbs and a relatively high fat intake), and moving gradually to a Phase 3 (more carb-permissive and lower in fat). Ludwig recently spoke to Runner’s World about results published in his book, why calorie-counting often fails, and foods to avoid to jump-start weight loss.

Runner’s World: Why have obesity rates climbed so high in the last 30 years?

David Ludwig: Obesity rates were flat for decades, then began an unrelenting upswing in the 1970s. Diet and lifestyle have changed in many ways, so we can’t know exactly how much any single factor has contributed. But it’s hard to ignore that the low-fat craze got started in the 1970s. Our highly-processed, industrial carbohydrates raise insulin levels, which drive fat cells into kilojoule-storage overdrive.

RW: Do you believe in the kilojoules in/kilojoules out thermodynamics, or do you believe in a different dynamic?

DL: Ultimately, to lose weight, we need to take in fewer kilojoules than we burn off. However, the common misconception is that we have conscious control over the underlying biological processes. The kilojoule in/kilojoule out model works for a toaster oven, but humans aren’t machines. The fundamental problem in obesity isn’t too many kilojoules stored in fat, it’s too few in the blood stream, where it will be available to fuel the body’s needs. When we cut back kilojoules on a conventional low-fat diet, we only make this situation worse, creating a battle between mind and metabolism that we’re destined to lose.

RW: Can you name three foods that, if eliminated from the diet, would help people launch into a successful weight-loss program?

DL: First, white potatoes. Yams and sweet potatoes are okay, because they raise blood sugar much less. Second, highly processed grains. I’m talking about breads, white rice, and most breakfast cereals. Third, added sugars, in all their many forms—from soft drinks to yoghurts to muffins, and many more. If people reduce these foods, and substitute healthy fats (nuts, olive oil, avocado, dark chocolate) and natural carbohydrates (vegetables, fruits, legumes), their metabolism will change, and they will be able to lose weight without hunger.

RW: Your book seems similar to other low-carb books. What are some important differences?

DL: Very low-carbohydrate diets have been shown to be more effective, at least up to one year, compared to conventional low-fat diets. The reason is that they lower levels of the hormone insulin, which I call the ultimate fat cell fertiliser. In general, reducing carbohydrates to very low levels is the fastest way to reduce insulin and reprogram fat cells for kilojoule release, not storage. For this reason, we reduce carbohydrate to 25 per cent in Phase 1 of the program (two weeks). Over the long term, we find that severe carbohydrate restriction isn’t usually necessary. That’s a big difference in my program versus other low-carb diets. Research from my group in the November issue of the journal Obesity showed that after just one month of carbohydrate restriction, metabolism improves, allowing for increased carbohydrate intake without adverse effects on calorie expenditure.

RW: You’re quite insistent about the importance of sleep, activity, stress control, and behavioral psychology. Why?

DL: Beyond diet, several aspects of our modern lifestyle can adversely affect fat cell behavior, leading to excessive fat storage and chronic inflammation. The most important of these are sleep deprivation, persistent stress, and too much sedentary time. We recommend physical activities for everyone, not specifically to burn kilojoules, but rather to improve insulin resistance and lower chronic inflammation. These benefits can be obtained with relatively low intensity activities, like moderate-paced walking. Many Italians take a leisurely stroll after dinner—the passeggiata. This is a very enjoyable and rewarding practice because it comes after the largest meal of the day and reduces the insulin produced by such a meal.

RW: Most diets fail after six to 12 months, probably because they increase hunger and decrease metabolic rate. How is the solution in your book different?

DL: The Always Hungry? program works from the inside out, without kilojoule restriction, by shifting metabolism toward optimal functioning. This way, your body (not a diet-book doctor) determines what rate of weight loss is right for you. Some participants in our national pilot initially lost one kilogram a week or more. But without increased hunger, these results are progressive and sustainable.

RW: Have you ever had a weight problem? What did you do?

DL: I was lean and fit in early adulthood, and ate what was generally considered a healthy diet at the time. In my 20s, I began putting on an extra kilo or two each year. At that point I decided to practice what my research was showing. I cut way back on processed carbohydrates, doubled my intake of fat, and increased protein slightly. I made no attempt to limit all carbs or to cut kilojoules. Within days, I felt a remarkable surge in energy and was less hungry. After three months, I needed a new wardrobe, including pants that were two waist sizes smaller. I’ve maintained that diet and my weight loss to this day.

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