What Really Makes Us Fat


Introduction Questions (answer in the comments section below):

  1. Do you think that eating fat makes you fat? Why or why not?
  2. Do you think that a low-fat diet is a good way to lose weight? Why or why not? 
  3. Do you think that a high-fat diet could actually help you lose fat? Why or why not?

Key Vocabulary:


a. To break down calories to make energy

2. Obesity

b. Low level of sugar

3. Metabolize

c. Traditional Knowledge

4. Carbohydrate

d. Always

5. Invariably

e. Fatness

6. Conventional Wisdom

f. Units of energy

7. Low Glycemic Index

g. Sugars, starches, and fibers found in grains, vegetables, and fruits


Main Idea Question (skim article to answer main idea question):

According to the article, what does the author imply really makes us fat?

Read the Article

Reading Strategies:

  • Skim (read quickly) the entire article for the main idea before reading for detail: Read the article quickly to get the main idea of the entire article before answering the following detail questions.
  • Do not stop for words you do not know: As you read, do not stop for words you do not know. Underline or note the word or phrase, guess from context, and move on. If you think it is a useful word or phrase, come back to it later and look up the meaning.
  • Write 1-3 words summarizing the main idea of each paragraph as you read: As you read (not afterward) write down a note (around 1-3 words) for each paragraph you read summarizing its main idea. After you read for the main idea, then read a second time more carefully to answer the detail questions.

What Really Makes Us Fat

A calorie is a calorie. This truism has been the foundation of nutritional wisdom and our beliefs about obesity since the 1960s.

What it means is that a calorie of protein will generate the same energy when metabolized in a living organism as a calorie of fat or carbohydrate. When talking about obesity or why we get fat, evoking the phrase “a calorie is a calorie” is almost invariably used to imply that what we eat is relatively unimportant. We get fat because we take in more calories than we expend; we get lean if we do the opposite. Anyone who tells you otherwise, by this logic, is trying to sell you something.

But not everyone buys this calorie argument, and the dispute erupted in full force again last week. The Journal of the American Medical Association published the results of a clinical trial by Dr. David Ludwig of Boston Children’s Hospital and his collaborators. While the media tended to treat the study as another diet trial — what should we eat to maintain weight loss? — it spoke to a far more fundamental issue: What actually causes obesity? Why do we get fat in the first place? Too many calories? Or something else?

UNTIL the 1960s, carbohydrates were indeed considered a likely suspect in obesity: “Every woman knows that carbohydrate is fattening,” as two British dietitians began a 1963 British Journal of Nutrition article.The obvious mechanism: carbohydrates stimulate secretion of the hormone insulin, which works, among other things, to store fat in our fat cells. At the time, though, the conventional wisdom was beginning its shift: obesity was becoming an energy issue.

Carbohydrates, with less than half the calories per gram as fat, were beginning their official transformation into heart-healthy diet foods. One reason we’ve been told since to eat low-fat, carbohydrate-rich diets is this expectation that they’ll keep us thin.

A clinical trial was done on three different groups who ate three different diets. One diet was low-fat and thus high in carbohydrates. This was the diet we’re all advised to eat: whole grains, fruits, vegetables, lean sources of protein. One diet had a low glycemic index: fewer carbohydrates in total, and those that were included were slow to be digested — from beans, non-starchy vegetables and other minimally processed sources. The third diet was Atkins, which is very low in carbohydrates and high in fat and protein.

The results were remarkable. Put most simply, the fewer carbohydrates consumed, the more energy these weight-reduced people expended. On the very low-carbohydrate Atkins diet, there was virtually no metabolic adaptation to the weight loss. These subjects expended, on average, only 100 fewer calories a day than they did at their full weights. Eight of the 21 subjects expended more than they did at their full weights — the opposite of the predicted metabolic compensation.

On the very low-carbohydrate diet, Dr. Ludwig’s subjects expended 300 more calories a day than they did on the low-fat diet and 150 calories more than on the low-glycemic-index diet. As Dr. Ludwig explained, when the subjects were eating low-fat diets, they’d have to add an hour of moderate-intensity physical activity each day to expend as much energy as they would effortlessly on the very-low-carb diet. And this while consuming the same amount of calories. If the physical activity made them hungrier — a likely assumption — maintaining weight on the low-fat, high-carb diet would be even harder.  Why does this speak to the very cause of obesity?

The fewer carbohydrates we eat, the more easily we remain lean. The more carbohydrates, the more difficult. In other words, carbohydrates are fattening, and obesity is a fat-storage defect. What matters, then, is the quantity and quality of carbohydrates we consume and their effect on insulin.

From this perspective, the trial suggests that among the bad decisions we can make to maintain our weight is exactly what the government and medical organizations like the American Heart Association have been telling us to do: eat low-fat, carbohydrate-rich diets, even if those diets include whole grains and fruits and vegetables.

Detail Questions (the answers are located in order as you read the article):

  1. What is accepted as a truism?
  1. What does ‘a calorie is a calorie’ imply?
  1. What were the diets the three different groups went on?
  1. What did those eating the low-fat diets have to do?
  1. According to the author, what are among the bad decisions that we can make?

Writing Response:

Different prompts to respond to (choose one or more):

  • What do you think about the author’s conclusion? Do you agree or disagree?
  • Critically evaluate: what do you think about the author’s argument? Did he make his point clear with strong support? 
  • Your Opinion: What do you think is the best diet to be less fat? One that has low sugar, low carbohydrates, low fat, or what? Why do you think obesity is a problem in today’s societies? 

Writing Strategies:

  • Make a quick outline: first, you can use different strategies to brainstorm. Then, clearly state your opinion/argument/main idea of your essay. From there, make an outline with 1-2 sentences of what the main paragraphs of your essay will include (the intro, body, and conclusion paragraphs).
  • Write the intro: include a hook (an interesting introductory sentence to capture the reader’s attention), some supporting info, and a thesis statement (stating your opinion/argument).
  • Write body paragraphs: remember to include a topical sentence (stating the main idea of the paragraph) as well as a transitional sentence (one that will transition well to the next paragraph).
  • Conclusion: here you want to summarize your opinion/argument/main idea of the essay, and end strongly with a concluding statement.