The concept of food combining, popularized by the book Fit For Life by Harvey and Marilyn Diamond, suggests that eating certain foods together can improve digestion, boost energy levels, and even aid in weight loss. The general principle revolves around easing digestion by simplifying meals and being mindful of food pairings. While scientific research on food combining is limited and anecdotal, many individuals find it a helpful tool for improving their overall well-being.
Understanding the Basics of Food Combining
Food combining is based on the idea that the body releases different enzymes to digest carbohydrates, proteins, and fats. Consuming too many dense foods at once may overwhelm the digestive system, leading to slowed digestion and fatigue. The goal is to choose one main food category per meal and combine it with non-starchy vegetables.
Megan, a Certified Nutritionist Consultant (CNC) and cookbook author, explains that food combining helped her eat more real foods regularly without restricting food groups. As she puts it, "I could eat anything I wanted, just not necessarily all at once."
Core Principles of Food Combining
While food combining principles vary among experts, a simplified version serves as a good starting point:
- Fresh Fruit: Most plans recommend eating fresh fruit on an empty stomach, usually in the morning, because it digests quickly.
- Starches: This category includes winter squash, sweet potatoes, avocados, beans, lentils, and all grains, including oatmeal, rice, quinoa, and buckwheat.
- Protein: Primarily includes animal protein, such as eggs, dairy, meat, and fish, as well as tofu.
- Nuts, Seeds + Dried Fruit: This category includes all nuts and seeds, as well as dried fruits like raisins and dates. Some suggest that bananas can be enjoyed with nuts.
- Non-Starchy Vegetables: You can pair any of the above categories with non-starchy vegetables, like carrots, cauliflower, zucchini, or broccoli. A good way to determine if a vegetable is non-starchy is to see if it can be consumed raw.
Practical Application: Building Properly Combined Meals
To create a properly combined meal, choose one category from the list above and only eat foods from that category for that particular meal. Here are some examples of properly combined meals:
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- Veggie Sandwich: Whole-grain bread filled with avocado, mustard, lettuce, tomato, and sprouts, served with a leafy side salad and a baked sweet potato topped with butter.
- Pasta with Vegetables:
- Quinoa Salad: Any grain-based salad topped with beans, veggies, and avocado.
- Baked Potatoes: Sweet potatoes or white potatoes topped with veggie chili.
- Soup: Hearty vegetarian soups, like Lentil Soup or Black Bean Soup.
- Meat and Fish Entrees: Baked chicken breasts or baked salmon over a large, leafy green salad, or with a side of roasted cauliflower or broccoli.
- Veggie Pizza Crusts: Cauliflower pizza crust or zucchini pizza boats topped with cheese and your favorite toppings.
- Spiralized or Shredded Pasta Alternatives: Sautéed cabbage, a bed of steamed cauliflower, or zucchini noodles with your favorite meatballs or meat-based spaghetti sauce on top.
- Salad with Nuts: A large leafy green salad topped with dried cranberries and raw walnuts, along with plenty of extra non-starchy vegetables.
- Bean-Free Hummus: Zucchini hummus served with sliced veggies as an appetizer for a nut-based meal.
- Grain-Free Breakfast Cereal: Paleo Granola topped with almond milk.
- Nut-Based Desserts: A slice of raw cheesecake or a coconut macaroon after your nut-based meal.
- Fruit Smoothies: Fruit can be combined with other fruits and leafy greens in a smoothie made with your favorite non-dairy milk.
The Role of "Magic" or "Star" Foods
Certain foods, often referred to as "magic" or "star" foods, can be combined with any other food group. These include:
- "Vegetable fruits": Avocados, cucumbers, tomatoes, bell peppers, and olives.
Timing and Fruit Consumption
When consuming fruit, adhering to food combining principles and timing matters. After eating fruit with nuts, seeds, and/or leafy greens, wait about 60 minutes before consuming animal protein or non-starchy vegetables.
Traditional food combiners consumed only fruit before noon, believing that fruit supports better detox and elimination as digesting fruit doesn’t require action by the liver. Fruit is a great replenisher of fluids after a night of rest and moves quickly from the stomach into the small intestine.
It's worth noting that some experts, including dietitians, do not advocate eating fruit on its own, as the natural sugar can cause blood sugar spikes followed by crashes, potentially leading to inflammation and fatigue. Fruit also does not sustain most people until the next meal or snack.
While most fruits move through the body in about 30 minutes, bananas and pears typically take about 40 minutes. Many people experience extreme gas and bloating when eating melon, particularly when they consume melon with other fruits in a smoothie or with nuts and seeds. Experiment, and see what works for you.
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Unfortunately, fruits (except for the magic/star fruits) do not combine well with concentrated starches and proteins, which typically take three to five hours to digest.
Food Combining and Exercise
If you’re trying to lose weight, it’s important to make sure you aren’t consuming additional calories your body doesn’t need. That means trying to time your meals or snacks around your workouts so you aren’t eating extra snacks for the sake of the workout.
Exercising on an empty stomach can help you burn more body fat for fuel. When you eat right before exercising, your body is going to first use the calories you just consumed for fuel. By exercising when it’s been about three to four hours since you last ate, your body is more able to burn fat for fuel because other easier methods of fuel aren’t available. Remember, before exercising, check your glucose levels to make sure you’re within a safe range to do so-about 100 to 180 mg/dL. This can be a very helpful weight-loss tool because regardless of how many calories you burn during your workout, you’re ensuring that you’re burning more body fat for fuel.
If you want to eat before exercising, choose a small snack or light meal. If exercising on an empty stomach isn’t a great fit for you, you can avoid consuming extra calories by simply timing your workout right after a small snack or a light meal.
What should you eat? Stick with real food. It doesn’t need to be complicated. Often, combining a carbohydrate source with a protein source is recommended. Some examples include:
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- Fruit + protein (examples: apple with a tablespoon of peanut butter, berries, and a few slices of turkey or nuts)
- Starch + protein (examples: whole grain crackers and cheese or 1/2 sandwich)
- Light yogurt
- A lighter snack of veggies and hummus, dip, or string cheese may be desired.
Don’t force yourself to eat a “post workout meal” for low-intensity exercise. If you’re trying to lose weight and your workouts are lower in intensity (like power walking, jogging, or cycling less than an hour at a time) then you likely do not need an intentional “post-workout meal”. Instead, strive to eat mostly whole foods every four to five hours throughout the day to support your calorie needs while also getting daily exercise.
For some types of exercise, it’s important to eat a meal (or a protein shake) within the hour after your workout. Types of exercise that might call for an immediate post-workout protein shake or meal include:
- Weight-lifting
- High intensity interval training
- Endurance training (long-distance running, cycling, etc.)
- Any intense exercise over 60 minutes
- High-intensity competitive sports (soccer, tennis, racquet ball, etc.)
If you don’t eat a substantial meal or post-workout protein shake after high intensity exercise, a few issues are of concern:
- You’re depriving your muscles of the amino acids they need to rebuild and recover.
- You’re not replenishing the stored glucose (glycogen) in your muscles which can lead to further muscle breakdown.
- You’ll get hungry a few hours later and likely overeat at that later meal.
The Hay Diet: A Historical Perspective
The Hay Diet, developed by Dr. William Howard Hay in the 1920s, is a specific type of food combining that separates food into three groups: alkaline, acidic, and neutral. Acidic foods (protein-rich) are not combined with alkaline foods (carbohydrate-rich). Hay believed that this separation aided digestion and improved health.
Hay's System promoted eating three meals per day with meal one being what the diet considers to be alkaline foods only, meal two composed of what the diet considers to be protein foods with salads, vegetables and fruit, and meal three composed of what the diet considers to be starchy foods with salads, vegetables and sweet fruit; with an interval of 4.0 to 4.5 hours between each meal.
While the Hay Diet gained popularity, it's important to note that current scientific understanding considers the theory that carbohydrate and protein-rich foods should be eaten separately as "unfounded" because it ignores the fact that carbohydrate-rich foods often contain significant amounts of protein.
Scientific Evidence and Considerations
It's crucial to approach food combining with a critical eye. While some individuals report positive experiences, scientific evidence supporting its effectiveness is limited.
One study has shown that humans tend to overeat when offered a wide variety of foods during a meal. By simplifying our meals, we will naturally eat less, without needing to count calories or worry about portion sizes. This might be why people see success in weight loss when following food combining principles.
One study suggests that primarily eating protein at lunch and then mostly carbohydrates at dinner could have a positive impact on diet-induced thermogenesis (the number of calories burned from digestion) and glucose levels. In this study, eating primarily carbs at lunch and then protein at dinner had a negative impact on glucose, so this may suggest that timing matters when you choose a food category.
We know that the body releases different enzymes to digest carbohydrates vs proteins. It stands to reason that if you eat primarily from one category, fewer enzymes will need to be released, thereby easing the digestive process.
It's essential to listen to your body and observe how different food combinations affect you individually. Food combining should not be used as a substitute for a balanced and varied diet.
Potential Benefits and Drawbacks
Potential Benefits:
- Increased mindfulness about food choices.
- Simplification of meal planning.
- Potential for reduced bloating and improved digestion for some individuals.
- Encouragement of increased vegetable consumption.
Potential Drawbacks:
- Limited scientific evidence to support its claims.
- May lead to unnecessary food restrictions if followed too rigidly.
- Can be challenging to implement in social situations or when eating out.
- Potential for nutrient deficiencies if not carefully planned.